Intel's Ian Romanick has just called for Mesa 7.9 to be released by the end of September, to satisfy the Intel driver release schedule of shipping new driver updates on a quarterly basis. Intel really wants Mesa 7.9 as part of their Q3'2010 update since it provides their new GLSL compiler, among other enhancements.
In terms of the new GL Shading Language compiler that was developed by Intel, it's not yet perfect and stabilized, but it's getting beaten into shape and the regression count is beginning to drop. Ian is confident that Mesa 7.9 can be shipped by month's end with this new compiler.
Mesa 7.8 was released all the way back in March and since then the code-base for 7.9 has received many Gallium3D support improvements, more work towards OpenGL 3.0 support, the new GLSL compiler, and other core Mesa enhancements.
In the Gallium3D land we now have MSAA anti-aliasing, Stream Out support, the ATI R600g driver that is starting to work, Nouveau driver improvements, ATI Evergreen Mesa code, support for the Wayland Display Server, improved ATI R300g support, LLVMpipe driver improvements, and so many other architectural changes and enhancements to the different drivers.
The related mailing list thread discussing this planned release of Mesa 7.9 by the end of September can be found on Mesa-dev.