VirtualBox v4.0.0 Final is released. VirtualBox is a general-purpose full virtualizer for x86 hardware. Targeted at server, desktop and embedded use, it is now the only professional-quality virtualization solution that is also Open Source Software.

VirtualBox v4.0.0 Final Changelog:
GuestControl: fix copying of small files
GUI: don't allow hitting the Finish button on the different wizards multiple times
GUI: don't show the inaccessible media warning when the user opens the VM settings
VBoxManage: accept relative paths for hard disk/DVD/floppy media
Linux Additions: fixed a problem which prevented loading the guest kernel modules under certain circumstances (Beta 4 regression)
Linux Additions: fixed resizing of additional displays (Beta 4 regression)
Linux Additions: fixed crash when switching users (4.0 regression)
Linux Additions: fixed regular crashes in X.Org in some guests (4.0 regression)
Guest Additions: fixed a memory leak in the display update code (4.0 regression)

Download: VirtualBox v4.0.0 Final
Source: Here