Ubuntu has release a new beta Version 10.10. If your interested in checking it out here are some details on installing and some information on how to get it to work on VirtualBox

To upgrade from Ubuntu 9.04 on a desktop system, press Alt+F2 and type in “update-manager -d” (without the quotes) into the command box. Update Manager should open up and tell you: New distribution release ’9.10′ is available. Click Upgrade and follow the on-screen instructions.

If you are running this on VirtualBox you may run into a bump in the road the VboxAdditions doesn't yet support the new desktop however unixmen has found a solution.

sudo apt-get update sudo apt-get install build-essential linux-headers-$(uname -r) sudo apt-get install virtualbox-ose-guest-x11