I was recently doing some testing of r300 vs. fgrlx for one of 
the compiz dev's when I noticed that the reflection plugin no longer (with 
mesa from git) works on my x700 even though it worked fine with mesa 7.0.1.  
After a little bit of git-bisecting and recompiling xf86-video-ati and 
xserver, I managed to locate the commit where it broke:

# bad: [c34b024cf49f3fc06271d561a4069c77d7b65c48] r300: add artificial output 
to match fragment program input

Onestone (from #compiz-fusion-dev) says that the shader 'fragment.position' 
attribute must be broken.