Today's committed work doesn't exactly bring any support breakthroughs with the R600 DRI driver, but after the developers were testing the driver they found most of the OpenGL 2.1 / GLSL 1.20 tests were passing fine and thus decided to set the flag officially enabling GLSL 1.20 (via this commit) while most of the OpenGL 2.1 extensions have been supported by this open-source driver for a period of time. This change though may help those with Wine and running other games/applications that prefer using OGL v2.1 / GLSL v1.20.
There's already been OpenGL 2.1 support for ATI Radeon R300 through R500 ASICs when using the R300g Gallium3D driver with the Mesa state tracker, but this is good news for those using the R600 classic Mesa driver. While the R600 Gallium3D driver isn't up to the same point as its classic Mesa counterpart, it hit the glxgears milestone late last month and since then gained OpenGL texture support and mip-map and face culling support along with other capabilities.
All of this work will be present in the upcoming Mesa 7.9 release.