On Monday there was a request by Marek Olšák to either delay the branching of Mesa 9.0 by about one week or to allow him to push some feature changes into the 9.0 branch. Marek's interested in bringing support for MSAA to more Radeon GPUs. He's landed the multi-sample anti-aliasing (MSAA) support for the Radeon HD 5000 "Evergreen" GPUs into Mesa recently but he's nearly done with enabling the anti-aliasing support for more Radeon graphics cards on R600g.
Ian Romanick, the current Mesa release manager, responded with a brief message: "Yeah, that is fine... I'm lagging a bit and need a few more days too."
In the past few days there's been more Intel Mesa patches hitting the list, so there should be a few more features squeezed in before branching this next Mesa release. Mesa 9.0 was expected to be released in about four weeks time, but now it looks like that the mid-September release is in jeopardy.
Assuming this doesn't make the Ubuntu developers decide against shipping Mesa 9.0 in Ubuntu 12.10 (they're still on Mesa 8.0.4 in the Ubuntu Quantal repository at the moment), the delay shouldn't be much of a problem. For enthusiasts reading Phoronix, due to Mesa being in a constant game of catch-up against the proprietary graphics drivers and against the latest upstream Khronos API specifications (OpenGL, OpenGL ES, OpenCL, etc), I generally always recommend running Mesa Git master. Mesa Git master tends to usually be in a sane state and better off -- in terms of features and performance -- than whatever is the current stable release for this open-source graphics library.