Most notably, Marek added Texture Buffer Object and Uniform Buffer Object support. With the OpenGL TBO/UBO support, GL Shading Language 1.40 compliance was reached.
Other RadeonSI Gallium3D driver changes were also made and then long story short, Marek updated its GL3 status. Where is RadeonSI at now? OpenGL 3.3 support has been reached for RadeonSI except for geometry shaders and GLSL 1.50 (correction: so for right now it's limited to OpenGL 3.1 officially but near to GL 3.3).
Before getting too excited and rebuilding Mesa Git master straightaway, you will also need to be using the LLVM 3.4 SVN code for the AMD GPU LLVM back-end that's needed by RadeonSI.
It's great to see RadeonSI catching up to R600g when it comes to OpenGL compliance, but R600g remains much faster and more mature while the RadeonSI Gallium3D performance is still lagging behind. At least with Mesa 10.0 when released in a few weeks time the RadeonSI driver is in a much better state than found with Mesa 9.2 stable.