Guest SMP with up to 32 virtual CPUs (VT-x and AMD-V only; see chapter 3.7.2.2 of the user manual)
Windows guests: ability to use Direct3D 8/9 applications / games
Support for OpenGL 2.0 for Windows, Linux and Solaris guests

Solaris hosts: allow suspend/resume on the host when a VM is running (bug #3826)
Solaris hosts: loosen the restriction for contiguous physical memory under certain conditions
Mac OS X hosts: fixed guest PAE
Linux hosts: kernel module compile fixes for 2.6.31 (bug #4264)
VMM: fixed occasional guru meditation when loading a saved state (VT-x only)
VMM: eliminated IO-APIC overhead with 32 bits guests (VT-x only, some Intel CPUs don’t support this feature (most do); bug #638)
VMM: fixed 64 bits CentOS guest hangs during early boot (AMD-V only; bug #3927)
VMM: performance improvements for certain PAE guests (e.g. Linux 2.6.29+ kernels)
VMM: some Windows guests detected a completely wrong CPU frequency (bug #2227)
VMM: fixed hanging and unkillable VM processes (bug #4040)
VMM: fixed random infrequent guest crashes due to XMM state corruption (Win64 hosts only)
VMM: performance improvements for network I/O (VT-x/AMD-V only)
GUI: added mini toolbar for fullscreen and seamless mode (Thanks to Huihong Luo)
GUI: redesigned settings dialogs
GUI: allow to create/remove more than one host-only network adapters (non Windows hosts)
GUI: display estimated time for long running operations (e.g. OVF import/export)
GUI: fixed rare hangs when open the OVF import/export wizards (bug #4157)
3D support: fixed VM crashes for client applications using incorrect OpenGL states
3D support: fixed memory corruption when querying for supported texture compression formats
3D support: fixed incorrect rendering of glDrawRangeElements
3D support: fixed memory leak when using VBOs
3D support: fixed glew library detection
3D support: fixed random textures corruption
VRDP: support Windows 7 RDP client
Networking: fixed another problem with TX checksum offloading with Linux kernels up to version 2.6.18
NAT: fixed “open ports on virtual router 10.0.2.2 - 513, 514” (forum)
NAT: allow to configure socket and internal parameters
NAT: allow to bind sockets to specific interface
PXE boot: significant performance increase (VT-x/AMD-V only)
VHD: properly write empty sectors when cloning of VHD images (bug #4080)
VHD: fixed crash when discarding snapshots of a VHD image
VHD: fixed access beyond the block bitmap which could lead to arbitrary crashes
VBoxManage: fixed incorrect partition table processing when creating VMDK files giving raw partition access (bug #3510)
VBoxManage: support cloning to existing image file
OVF: several OVF 1.0 compatibility fixes
OVF: fixed exporting of disk images when multiple virtual machines are exported at once
Virtual mouse device: eliminated micro-movements of the virtual mouse which were confusing some applications (bug #3782)
Shared Folders: sometimes a file was created using the wrong permissions (2.2.0 regression; bug #3785)
Shared Folders: allow to change file attributes from Linux guests and use the correct file mode when creating files
Shared Folders: some content was incorrectly written under certain conditions (bug #1187)
Shared Folders: fixed incorrect file timestamps, when using Windows guest on a Linux host (bug #3404)
X11 clipboard: fix duplicate end of lines (bug #4270)
X11 guests: a number of shared clipboard fixes
Linux guests: Guest Additions support for SUSE Linux Enterprise Desktop 11
Linux guests: new daemon vboxadd-service to handle time synchronization and guest property lookup
Linux guests: implemented guest properties (OS info, logged in users, basic network information)
Windows host installer: VirtualBox Python API can now be installed automatically (requires Python and Win32 Extensions installed)
USB: Support for high-speed isochronous endpoints has been added. In addition, read-ahead buffering is performed for input endpoints (currently Linux hosts only). This should allow additional devices to work, notably webcams (bug #242).
USB: fixed error handling for some USB dongles
Web service: fixed inability to handle NULL pointers for object arguments, which are valid values for a lot of APIs, in both the raw and the object-oriented web service.
Web service: object-oriented bindings for JAX-WS did not exhibit interface inheritance correctly, fixed
Web service: added support for IDisplay and IGuest interfaces, which were previously unavailable
Registration dialog uses Sun Online accounts now

Windows Installer: fixed a potential hang during installation
Windows Installer: fixed several problems

Solaris hosts: make it work with Solaris build 114 or later
Solaris hosts: fixed a bug serial port character handling found during loopback

Linux hosts: adapted vboxdrv.sh to the latest changes in VBoxManage list runningvms
Windows hosts: fixed a crash caused by host-only/bridged networking

Mac OS X hosts: fixed access to host DVD with passthrough disabled

Guest Additions: fixed problems with KDE 4 not recognizing mouse clicks
Windows Additions: fixed incorrect 8-bit guest color depth in Windows 7 guests

GUI: warn if VT-x/AMD-V could not be enabled for guests that require this setting

VMM: fixed occassional crash due to insuffient memory
VMM: fixed hanging 64 bits Solaris guests
VMM: restore from a saved state occassionally failed (bugs #3984 and #2742)

Clipboard: fixed a deadlock while shutting down the shared clipboard on X11 hosts

OVF: fixed potential hang during import
OVF: fixed potential crashes during import/export on Win64 hosts

VBoxManage modifyhd –compact: fixed bug which could lead to crashes and image corruption
VBoxManage metrics collect: now flushes the output stream.

VHD: made VBoxManage internalcommands sethduuid work for .vhd files (bug #3443)
VHD: some .vhd files could not be cloned (bug #4080)
VMDK: fixed creating snapshots

NAT: improvement of TCP connection establisment (bug #2987)
NAT: fixed order of DNS servers in DHCP lease (bug #4091)
NAT: fixed DHCP lease for multiple name servers (bug #3692)
NAT: fixed a potential segfault if the host lost its connectivity (bug #3964)

Shared Folders: deny access to parent directories on Windows hosts (bug #4090)
Shared Folders: make rm/rmdir work with Solaris guests on Windows hosts

Networking: fixed the problem with blocked receiving thread when a broadcast packet arrives too early to be handled by uninitialized e1000 adapter.
Networking: fixed the problem that caused host freezes/crashes when using bridged mode with host’s interface having RX checksum offloading on (bug #3926 and related). Fixes problems with TX offloading as well (bug #3870)

PXE boot: Added support for PRO/1000 MT Server adapter.
Python bindings: fixed keyword conflict
SCSI: fixed occasional crashes on Win64
Serial: allow to redirect the serial port to a raw file (bug #1023)
VRDP: fixed a rare incorrect screen update

Host and guest clipboard: fixed a number of issues affecting hosts and guests running the X window system.

Guest Additions: make sure the virtual mouse autodetection works on first reboot after installing the Additions on X.Org server 1.5 and later.
Guest Additions: properly report process identity number of running services
Guest Additions: clean up properly if the X Window server terminates

Linux Additions: fixed installation path for OpenGL libraries in some 64-bit guests

Solaris Additions: fixed installation to work when X.Org is not installed on the guest
Solaris Additions: fixed a bug that could panic the guest when unmounting a busy shared folder

Windows Additions: fixed mouse pointer integration of some Windows guests (2.2.0 regression)
Windows Additions: fixed installation on Windows Server 2008 Core

Main: do not try to use older versions of D-Bus (Linux hosts only)

VMM: fixed out-of-memory conditions on Windows hosts
VMM: fixed occasional hangs when attaching USB devices during VM startup (2.2.0 regression)
VMM: fixed guru meditation related to memory management (software virtualization only)

Virtual disks: fix possible data corruption when writing to diff images, incorrect detection of redundant writes

GUI: reworked network settings dialog
GUI: properly show the detailed settings dialog of NAT networks
GUI: HostKey could not be changed (2.2.0 regression)
GUI: fixed memory textfield size (Windows hosts only)
GUI: fixed crash when selecting a shared folder path (Windows hosts only)

VBoxManage modifyhd –compact: implemented again for VDI files, and now supports relative paths
VBoxManage snapshot discard: made it work again (2.1.0 regression)

NAT: on some Windows host, the guest didn’t receive a DHCP lease
NAT: fixed release assertion during poll()

Clipboard: fixed random crahes (X11 hosts only)
Shared Folders: fixed incorrect permissions for Solaris guests
Shared Folders: fixed wrong file sizes with Solaris guests
CBindings: fixed possible memory leak while releasing the IVirtualBox and ISession Objects
Solaris hosts: fixed host-only network interface incompatibility with nwam/dhcpagent
Windows installer: fixed several install and uninstall issues
Mac OS X hosts: preliminary support for Snow Leopard

New major features
- OVF (Open Virtualization Format) appliance import and export (see chapter 3.8, Importing and exporting virtual machines, User Manual page 55)
- Host-only networking mode (see chapter 6.7, Host-only networking, User Manual page 88)
- Hypervisor optimizations with significant performance gains for high context switching rates
- Raised the memory limit for VMs on 64-bit hosts to 16GB
- VT-x/AMD-V are enabled by default for newly created virtual machines
- USB (OHCI & EHCI) is enabled by default for newly created virtual machines (Qt GUI only)
- Experimental USB support for OpenSolaris hosts
- Shared folders for Solaris and OpenSolaris guests
- OpenGL 3D acceleration for Linux and Solaris guests (see chapter 4.8, Hardware 3D acceleration (OpenGL), User Manual page 70)
- Added C API in addition to C++, Java, Python and Web Services

Other additions, changes or bug fixes
VMM: FreeBSD guest related fix for V86 flags (bug #2342)
VMM: fixed guru meditation when booting an AsteriskNow Linux VM (bug #2342)
VMM: fixed PGMPOOLKIND_FREE guru meditation (bugs #3356, #3431)
VMM: fixed Windows XP boot hang (guest PAE + nested paging only)
VMM: allow mixing of VT-x/AMD-V and software virtualization
VMM: fixed extremely slow safe mode booting in e.g. Windows 2008 (VT-x/AMD-V only)
VMM: significant speedup of certain GRUB boot loaders (e.g. Solaris) (VT-x/AMD-V only)
VMM: real-mode IOPL fix for DOS guests (VT-x only)
VMM: fixed VT-x detection with certain BIOSes that enable VT-x, but don’t set the lock bit in MSR_IA32_FEATURE_CONTROL
VMM: fixed hibernation issues on Windows XP hosts (VT-x only; bug #1794)
VMM: properly emulate RDMSR from the TSC MSR, should fix some NetBSD guests
VMM: emulate RDPMC; fixes Windows guests crashes when using the Kaspersky virus scanner (bug #1778)
NAT: fixed truncated downloads (FTP) (bug #3257)
NAT: blocked UDP packets caused a crash (bug #3426)
NAT: allow to configure the next server and the boot file via VBoxManage (bug #2759)
IDE: fixed hard disk upgrade from XML-1.2 settings (bug #1518)
Hard disk: support more VMDK file variants (including fixed-size ESX server images)
Hard disks: refuse to start the VM if a disk image is not writable
USB: further reduced host CPU utilization for OHCI and EHCI; the “VBoxInternal/Devices/usb-ohci/0/Config/FrameRate” CFG key is no longer necessary and no longer supported
USB: fixed BSOD on the host with certain USB devices (Windows hosts only; bug #1654)
E1000: properly handle cable disconnects (bug #3421)
VRDP: fixed hangs when VRDP server is enabled or disabled in runtime
Shared folders: respect umask settings on Linux, OSX and Solaris hosts when creating files
X11 guests: prevented setting the locale in vboxmouse, as this caused problems with Turkish locales (bug #3563)
X11 guests: show the guest mouse pointer at the right position if the virtual desktop is larger than the guest resolution (bug #2306)
Linux additions: fixed typo when detecting Xorg 1.6 (bug #3555)
Solaris guests: added xpg4/xcu4 dependency to the guest additions installer (bug #3524)
Windows guests: bind the VBoxMouse.sys filter driver to the correct guest pointing device (bug #1324)
Windows hosts: fixed BSOD when starting a VM with enabled host interface (bug #3414)
Linux hosts: do proper reference counting to prevent unloading the vboxnetflt module as long as this code is in use (bug #3104)
Linux hosts: do not leave zombies of VBoxSysInfo.sh (bug #3586)
Linux installers: fixes for Slackware, Arch Linux and Linux from Scratch systems
Windows installers: combined installer executable which contains both (32- and 64-bit) architectures.
VBoxManage: less cryptic command-line error messages
VBoxManage list vms commands now default to compact format
VBoxManage controlvm dvdattach did not work if the image was attached before
VBoxManage: allow creation of all supported disk image variants
VBoxManage showvminfo: don’t spam the release log if the additions don’t support statistics information (bug #3457)
VBoxManage: big command line processing cleanup, the legacy single-dash options are deprecated and will be removed in the next major release, so switch to the new options now
Hard disks: improved immutable disk support to auto-reset diff file at VM startup (related to bug #2772)
GUI: enable the audio adapter by default for new VMs
GUI: warn if VT-x/AMD-V is not operational when starting a 64-bit guest
GUI: deactivate 64-bit guest support when the host CPU does not support VT-x/AMD-V
GUI: removed floppy icon from the status bar
GUI: show build revision in about dialog
GUI: fixed sticky status bar text
GUI: improved error dialogs
GUI: fail with an appropriate error message when trying to boot a read-only disk image (bug #1745)
GUI/Mac OS X: fixed disabled close button
GUI/Windows: re-enabled support for copy and paste (Windows hosts 2.0 regression; bug #2065)
3D support: added OpenGL select/feedback support (bug #2920)
3D support: close OpenGL subsystem for terminated guest applications (bug #3243)
3D support: fixed VM hangs when starting guests with 3D acceleration enabled (bug #3437)
PXE: fixed boot hangs when hardware virtualization is used (bug #2536)
LsiLogic: fixed problems with Solaris guests
Main API: close machine settings XML file when unregistering machine (bug #3548)

Windows hosts: fixed host crashes/hangs on certain 32 bits Windows systems when running Linux guests (bugs #1606, #2269, #2763)
Windows hosts: Fixed network component BSOD issue (bugs #3168, #2916)
Windows hosts: Fixed installation issues (bugs #2517, #1730, #3130)

Linux hosts: fixed occasional kernel oopses (bug #2556)
Linux hosts: fixed module dependency for shipped modules (bug #3115)
Linux hosts: moved the udev rules for USB forward so that they don’t override existing system rules (bug #3143)
Linux hosts: fixed the issue with guest not being able to communicate with each other when attached via TAP interfaces (bug #3215)
Linux hosts: give up probing for USB gracefully if dbus or hal are not available (bug #3136)
Linux hosts: fixed warnings in installer when SELinux was disabled (bug #3098)
Linux hosts: VirtualBox sometimes failed to start if it had been started using sudo previously (bug #3270)

Solaris hosts: fixed high CPU load while running many guests in parallel
Solaris hosts: fixed inability to start more than 128 VMs

VMM: fixed performance regression for Windows guests (bug #3172)
VMM: ignore CPU stepping when restoring a saved state/snapshot

REM: fixed inability to use gdb to debug programs in Linux guests with software virtualization (bug #3245)

GUI: fixed dead key handling on Solaris hosts (bug #3256)
GUI: in the shutdown dialog, disable the action send the shutdown signal if the guest is currently not using ACPI
GUI: suppress additional key release events sent by X11 hosts when keys are auto-repeated (bug #1296)

API: restore case insensitive OS type name lookup (bug #3087)

VBoxHeadless: really don’t start X11 services (clipboard service, 3D acceleration; Solaris & Darwin hosts only; bug #3199)

NAT: fixed occasional crashes when the guest is doing traceroute (non-Windows hosts; bug #3200)
NAT: fixed crashes under high load (bug #3110)
NAT: fixed truncated downloads (Windows hosts only, bug #3257)
NAT: don’t intercept TFTP packages with a destination address different from the builtin TFTP server (bug #3112)

USB: several fixes for USB passthrough on Linux hosts
USB: reduced host CPU utilization if EHCI is active

VRDP: fixed VRDP server black screen after a client reconnect (bug #1989)
VRDP: modified rdesktop client (rdesktop-vrdp) now uses NumLock state synchronization (bug #3253)

LsiLogic: make FreeBSD guests work (bug #3174)

ATA: fixed deadlock when pausing VM due to problems with the virtual disk (e.g. disk full, iSCSI target unavailable)

iSCSI: fixed possible crash when pausing the VM

3D support: added missing GL_MAX_TEXTURE_COORDS_ARB (bug #3246)

Windows Additions: fixed ERROR (e0000101) error during installation (bug #1923)
Windows Additions: fixed Windows Explorer hang when browsing shared folders with 64 bit guests (bug #2225)
Windows Additions: fixed guest screen distortions during a video mode change
Windows Additions: fixed the Network drive not connected message for mapped shared folders drives after the guest startup (bug #3157)

Linux Additions: fixed occasional file corruption when writing files in O_APPEND mode to a shared folder (bug #2844)
Linux Additions: the mouse driver was not properly set up on X.Org release candidates (bug #3212)
Linux Additions: fixed installer to work with openSUSE 11.1 (bug #3213)
Linux Additions: disable dynamic resizing if the X server is configured for fixed resolutions
Linux/Solaris Additions: handle virtual resolutions properly which are larger than the actual guest resolution (bug #3096)

USB: improved support for recent Linux hosts
VMM: fixed guru meditation for PAE guests on non-PAE hosts (AMD-V)
VMM: fixed guru meditation on Mac OS X hosts when using VT-x
VMM: allow running up to 1023 VMs on 64-bit hosts (used to be 127)
VMM: several FreeBSD guest related fixes (bugs #2342, #2341, #2761)
VMM: fixed guru meditation when installing Suse Enterprise Server 10U2 (VT-x only; bug #3039)
VMM: fixed guru meditation when booting Novell Netware 4.11 (VT-x only; bug #2898)
VMM: fixed VERR_ADDRESS_TOO_BIG error on some Mac OS X systems when starting a VM
VMM: clear MSR_K6_EFER_SVME after probing for AMD-V (bug #3058)
VMM: fixed guru meditation during Windows 7 boot with more than 2 GB guest RAM (VT-x, nested paging only)
VMM: fixed hang during OS/2 MCP2 boot (AMD-V and VT-x only)
VMM: fixed loop during OpenBSD 4.0 boot (VT-x only)
VMM: fixed random crashes related to FPU/XMM with 64 bits guests on 32 bits hosts
VMM: fixed occasional XMM state corruption with 64 bits guests
VMM: speed improvements for real mode and protected mode without paging (software virtualization only)
GUI: raised the RAM limit for new VMs to 75% of the host memory
GUI: added Windows 7 as operating system type
VBoxSDL: fixed -fixed fixedmode parameter (bug #3067)
Clipboard: stability fixes (Linux and Solaris hosts only, bug #2675 and #3003)
3D support: fixed VM crashes for certain guest applications (bugs #2781, #2797, #2972, #3089)
LsiLogic: improved support for Windows guests (still experimental)
VGA: fixed a 2.1.0 regression where guest screen resize events were not properly handled (bug #2783)
VGA: significant performance improvements when using VT-x/AMD-V on Mac OS X hosts
VGA: better handling for VRAM offset changes (fixes GRUB2 and Dos DOOM display issues)
VGA: custom VESA modes with invalid widths are now rounded up to correct ones (bug #2895)
IDE: fixed ATAPI passthrough support (Linux hosts only; bug #2795)
Networking: fixed kernel panics due to NULL pointer dereference in Linux kernels < 2.6.20 (Linux hosts only; bug #2827)
Networking: fixed intermittend BSODs when using the new host interface (Windows hosts only; bugs #2832, #2937, #2929)
Networking: fixed several issues with displaying hostif NICs in the GUI (Windows hosts only; bugs 2814, #2842)
Networking: fixed the issue with displaying hostif NICs without assigned IP addresses (Linux hosts only; bug #2780)
Networking: fixed the issue with sent packets coming back to internal network when using hostif (Linux hosts only; bug #3056).
NAT: fixed port forwarding (Windows hosts only; bug #2808)
NAT: fixed booting from the builtin TFTP server (bug #1959)
NAT: fixed occasional crashes (bug #2709)
SATA: vendor product data (VPD) is now configurable
SATA: raw disk partitions were not recognized (2.1.0 regression, Windows host only, bug #2778)
SATA: fixed timeouts in the guest when using raw VMDK files (Linux host only, bug #2796)
SATA: huge speed up during certain I/O operations like formatting a drive
SATA/IDE: fixed possible crash/errors during VM shutdown
VRDP: fixed loading of libpam.so.1 from the host (Solaris hosts only)
VRDP: fixed RDP client disconnects
VRDP: fixed VRDP server misbehavior after a broken client connection
VBoxManage showvminfo: fixed assertion for running VMs (bug #2773)
VBoxManage convertfromraw: added parameter checking and made it default to creating VDI files; fixed and documented format parameter (bug #2776)
VBoxManage clonehd: fixed garbled output image when creating VDI files (bug #2813)
VBoxManage guestproperty: fixed property enumeration (incorrect parameters/exception)
VHD: fixed error when attaching certain container files (bug #2768)
Solaris hosts: added support for serial ports (bug #1849)
Solaris hosts: fix for Japanese keyboards (bug #2847)
Solaris hosts: 32-bit and 64-bit versions now available as a single, unified package
Linux hosts: don’t depend on libcap1 anymore (bug #2859)
Linux hosts: compile fixes for 2.6.29-rc1
Linux hosts: don’t drop any capability if the VM was started by root (2.1.0 regression)
Mac OS X hosts: save the state of running or paused VMs when the host machine’s battery reaches critical level
Mac OS X hosts: improved window resizing of the VM window
Mac OS X hosts: added GUI option to disable the dock icon realtime preview in the GUI to decrease the host CPU load when the guest is doing 3D
Mac OS X hosts: polished realtime preview dock icon
Windows Additions: fixed guest property and logging OS type detection for Windows 2008 and Windows 7 Beta
Windows Additions: added support for Windows 7 Beta (bugs #2995, #3015)
Windows Additions: fixed Windows 2000 guest freeze when accessing files on shared folders (bug #2764)
Windows Additions: fixed Ctrl-Alt-Del handling when using VBoxGINA
Windows Additions Installer: Added /extract switch to only extract (not install) the files to a directory (can be specified with /D=path)
Linux installer and Additions: added support for the Linux From Scratch distribution (bug #1587) and recent Gentoo versions (bug #2938)
Additions: added experimental support for X.Org Server 1.6 RC on Linux guests
Linux Additions: fixed bug which prevented to properly set fmode on mapped shared folders (bug #1776)
Linux Additions: fixed appending of files on shared folders (bug #1612)
Linux Additions: ignore noauto option when mounting a shared folder (bug #2498)
Linux Additions: fixed a driver issue preventing X11 from compiling keymaps (bug #2793 and #2905)
X11 Additions: workaround in the mouse driver for a server crash when the driver is loaded manually (bug #2397)