The Ubuntu 9.10 "Karmic Koala" Alpha 1 is released on 14 may 2009 and available for download.
Ubuntu Testing
In addition to their six-monthly stable releases and our daily development builds, they also make regular testing releases during the development cycle. With just a few spare minutes, you can provide valuable feedback on a test release and help polish and stabilise. Please see the testing wiki page for more information on how to test and report back. Links to the test release downloads can be found on the pages listed below.
Please test the latest available edition. Thank you!
More info here
http://cdimage.ubuntu.com/releases/karmic/alpha-1/ (Ubuntu Alternates, Server, Netbook Remix, and MID)
http://cdimage.ubuntu.com/kubuntu/releases/karmic/alpha-1/ (Kubuntu)
http://cdimage.ubuntu.com/xubuntu/releases/karmic/alpha-1/ (Xubuntu)
http://cdimage.ubuntu.com/netboot/karmic/alpha-1/ (Ubuntu ARM)