Theres another thread trying to get psb/gma500 working on Ubuntu. It's not there yet but seems closeish.
Originally Posted by pinkflamingo8806
The Mandrivia people got it working on Xserver 1.7
So far there seems to be a hack to fix the resolution using non-psb drivers, but performance will of course be crap (or crappier). Add it to /etc/grub.d/40-custom:
I haven't tried it on the T91 yet.
915resolution 5c 1024 600
There is also still some hope that we will see working drivers, reportedly Intel are working on them, they are pushing their own Linux platform after all (unless the current drives we have are those). Another post with quake video.
The main issue right now might be the 2.6.33 backported DRI code that ended up in the 2.6.32 kernel shipped with Ubuntu.