All of the really exciting work is going to be released in Mesa 9.1, which is due out before month's end. Mesa 9.1 has performance improvements, better OpenGL support, improved stability, and a whole lot of other new features.
For those not trusting Git or even the 9.1 release candidates, Mesa 9.0.3 is available today. The release, which has its very brief announcement on the mailing list, just incorporates some stable bug-fixes.
For those wanting to find out about the bug-fixes and other changes that went into Mesa 9.0.3, they should check out this documentation commit.