I downloaded ubuntu 8.04.1 alternate install CD and installed Hardy Heron on the x200, sucessfully so far. Wireless did NOT work out of the box, however. And I have also issues with the Intel Graphics x4500. The Desktop itself seems to work nicely, but my tests with world of warcraft were disappointing, even though glxgear was pretty good.
Wireless wroked by using the firmware of iwl5000 and using compat-wireless (for kernel older than 2.6.27).
Guess I need to try Ubuntu 8.10 beta…can not really wait for the release…;)