Update: SUN xVM VirtualBox 2.2.2
xVM VirtualBox has been updated to 2.2.2.
Lots of fixes and changes, but nothing major (like 2.2.0). Ok, maybe the preliminary support for Snow Leopard is worth mentioning 
exe installer, 62.9MB, MD5 sum: 9E5C2D9A41C6C9B3E619C4FC21DE0B6E
Other stuff: VirtualBox for Linux, Mac, Solaris + SDKs and older versions
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