VirtualBox 1.4 released, download last version from here
For windows host click here
This new version brings hundreds of improvements, more than any update since the first official release in January 2007. Among the new features are full support for 64-bit Linux hosts, RDP session shadowing, clipboard synchronization and easier Linux host interface networking. In the storage department, VirtualBox now supports VMware disk images (VMDK) natively and can give virtual machines access to physical disks and partitions ("raw disk support"). The graphical user interface has received more polish and has now been translated into 12 languages (German, Spanish, French, Italian, Polish, Portuguese, Romanian, Arabic, Russian, Japanese, Traditional Chinese and Chinese). Red Hat Enterprise Linux 5 (RHEL5) and Xandros Desktop 4.1 are now officially supported; support for FreeBSD and OpenBSD guests has been improved.
As with its predecessors, VirtualBox 1.4.0 is available both as Open Source under the GPL as well as under a commercial license which, in most cases, allows you to use the product free of charge.
For user with 1.3.8 version, quick way to upgrade is by uninstalling 1.3.8 and reinstall 1.4, no reboot needed. (Forum)
I will try FreeBSD 6.2 and Solaris 10 in this release