For a few months now, Intel has been writing a new GLSL compiler for Mesa (they've dubbed it "GLSL2") that started out as a standalone GL Shading Language compiler that was then integrated into Mesa. Over the past month they now have better code being generated and they have written a complete linker that's nearly complete.
Intel's new GLSL compiler for Mesa isn't yet complete, but they want it in Mesa as part of their Intel 2010'Q3 driver package, which means that it needs to be merged into Mesa's mainline code-base and Mesa 7.9 then released before the end of the quarter.
Romanick is hoping to merge all of this code into Mesa by the end of August. Merging will take place as soon as the compiler is effectively complete and there are no piglit regressions and that the failing tests do not crash.
Intel has plans for this GLSL compiler to properly handle GLSL ES (GLSL for embedded systems) too, but that isn't yet complete and will likely come later.
Intel hasn't tested their new GLSL compiler with any other drivers besides their own Intel classic Mesa driver. They're hoping for the best that this new compiler will work well with the other drivers, including the classic ATI Radeon drivers and the assortment of Gallium3D drivers from Nouveau to LLVMpipe and Softpipe. The other drivers will hopefully work fine and not regress, but in particular the R300 GLSL compiler improvements that are being worked on this summer by a student developer participating in Google's Summer of Code, may differ.
Ian ends his mailing list message with, "We're already very close to our proposed merge criteria."