For many weeks already I've been writing at length about the new Mesa 10.0 features, which culminates with OpenGL 3.2/3.3 compliance for core Mesa and the Intel driver. There's also new hardware support, OpenGL performance improvements, and much more. In the days and weeks ahead will be more Phoronix articles covering the changes and more Git benchmarks.
The brief Mesa 10.0 Release Candidate 1 announcement, which doesn't go into any detail on the new features, can be found via the Mesa-dev mailing list. The next RC is planned for 22 November and hopefully shipping the final release on 27 November.