While core Mesa is capable now of OpenGL 3.3, OpenGL 3.0~3.1 support has been almost there in the LLVMpipe software driver for some time. One of the major blockers to advertising the GL3 capabilities of this software fallback driver was the lack of sample anti-aliasing support. This week David Airlie has proposed a "fake" MSAA patch to workaround the issue.
Earlier today the fake MSAA support patch for LLVMpipe was revised but now all it does is add a fake MSAA capability to Gallium3D but doesn't expose any multi-sample anti-aliasing levels. The patch also forces the extra extensions needed for OpenGL 3.2 compliance. Lastly, the patch raises the GL Shading Language version for LLVMpipe so that OpenGL 3.3 will be exposed.
This latest LLVMpipe activity can be found on the Mesa-dev list.
Separately, there's some LLVMpipe improvements living out-of-tree in the llvmpipe-rast-64 branch of Mesa Git. When these changes are merged they will, of course, be benchmarked at Phoronix.
These new LLVMpipe changes will likely be found in Mesa 10.1 (or potentially Mesa 11.0 should there be GL 4.0 support in core Mesa prior to the next release in three month's time).