I'm experiencing glitches with compiz (kde kicker has a white border above) when using latest mesa. I assume the glitches appear due to the fact that mesa and the in-xserver-mesa are out-of-sync. When upgrading both to git, glitches disappear. Building xorg-server-1.3 against mesa-7.0.1 is rather non-trivial, so I haven't tried that yet.
xorg-server 1.4 has landed