The RadeonSI Gallium3D driver is approaching a fairly usable state for open-source HD 7000 series support. The accelerated driver support still isn't very widespread since it basically needs the brand new Mesa 9.1 and also the R600 LLVM back-end, which for now requires a pre-release of LLVM 3.3 or Tom Stellard's LLVM branch and not an officially released version of the LLVM compiler infrastructure.
For those wanting to manually setup the RadeonSI Gallium3D stack on their system, a RadeonSI user guide was written within the forums. For a Radeon HD 7750 graphics card, the Phoronix reader reports that KDE desktop effects work and that Nexuiz runs at 22 FPS for a 1920 x 1200 resolution. Games the user experienced failure with were Rochard, Torchlight, and Lightsmark.
I've been meaning to run some new RadeonSI tests (the last time I tried 2+ months ago the driver was still in a miserable state) once finishing the Radeon HD 7850 Linux review that's coming soon.
a R600/SI scheduler patch by Michel Dänzer. With this minor patch, which is also material for possible back-porting to the Mesa stable branch, allows a few more apps to run/finish on the open-source AMD HD 7000 series GPU driver. Michel says the most notable applications htat should now work are Unreal Tournament 2004 and Lightsmark.