The wonderful Olivier Blin of Mandriva has come through with his patches for making the psb video driver for Poulsbo (GMA 500) chipsets work on newer versions of X.org. He reports success - including 3D - with X server 1.7.
I'm hoping this will mean I can provide fully-accelerated packages for Fedora 12 soon; I have to request an F12 branch in RPM Fusion, though, as I previously suppressed it to avoid anyone trying to use a driver that wouldn't work. So once that's created, I'll push the packages through.
F13 is more uncertain. It has an even newer X server - 1.8 - which Olivier doesn't have to test against, so we don't know if that works. It also has a newer Mesa which Olivier believes is likely to cause problems (due to the removal of a function the psb Mesa driver calls). He has an idea for a hack to get around this, but hasn't put it in place yet. So it's possible we won't be able to get a driver for F13 at all, and if we do, it'll likely be missing 3D acceleration, at least to start with. Still, better than a kick in the teeth.
There's a secondary problem with F13, which is that as far as RPM Fusion is concerned, F13 doesn't seem to exist. Fusion Rawhide is tracking Fedora Rawhide, which - under No Frozen Rawhide - is F14, not F13. There is no F13 branch in Fusion. So as far as I can tell, at present, there's just no way for me to provide F13 packages in RPM Fusion. It's very difficult for me to provide packages outside of RPM Fusion too, because I rely on the akmods system for packaging the kernel module, and that lives in RPM Fusion; with there being no F13 branch of RPM Fusion, there's no F13 akmods configuration - there's nowhere to source a set of the necessary packages from RPM Fusion for the akmods system to work. So, yeah, that sucks. Will report back if the situation improves!