Michel Dänzer, one of the new open-source employees at AMD, has sent in four patches that allow the Xorg state tracker to work with R600g. Two of the patches are to the state tracker itself while the other two are on the driver side. The patches landed to the mesa-dev mailing list but should be pushed into Git master soon for the eventual Mesa 7.12 release.
Using the Xorg state tracker is an alternative to using the classic xf86-video-ati DDX for the X.Org acceleration paths.
Committed to Mesa Git already this morning by Michel is another patch so that the Xorg state tracker now advertises XvMC (X-Video Motion Compensation) video playback support. Though XvMC isn't as interesting as the VDPAU state tracker that is already supported by the R600 Gallium3D driver.
In related news, there's also been recent work on restoring the XvMC support for the Nouveau driver with hardware acceleration. See this mailing list thread for those Nouveau XvMC details.