Last night I upgraded to Ubuntu 8.10. I must say it was a smooth upgrade, with all my own programs, like Second Life and Lotus Notes 8.5 beta 2,and my ATI card (!) still working perfectly after the process finished.
The current Second Life client however didn't perform well tonight. Earlier versions on 8.04 often made for a more smooth experience than Windows, but such that wasn't the case here. I don't know whether that had anything to do with Ubuntu, the SL client or Second Life itself however; I will reserve judgment on that until I have logged more user hours with it.
But, as I said, tonight it wasn't what it should be. Twice I lost an airplane while crossing a sim boundary, and I found myself alone in the dark skies, without a plane to pilot!