With Ubuntu 12.04 LTS the stock packages were tested (Linux 3.2 / Mesa 8.0.2 while running Unity), and then lastly we have the "Latest Git" tests. An Ubuntu 12.10 development snapshot from 6 June 2012 was installed with the Unity 5.12 desktop and other latest code while then manually building the latest libdrm / Mesa / xf86-video-ati / Linux Git from that day, which means the Linux 3.5 kernel, xf86-video-ati 6.14.99, and Mesa 8.1-devel. The last test was using these same Git components but running the OpenGL tests under the Unity 2D desktop, since for some hardware/drivers and some OpenGL workloads, Unity 2D performs better than the standard Unity desktop since Compiz does not get into the way. For the open-source driver testing, swap buffers wait was disabled but other settings were at their defaults.
In terms of any ongoing improvements to the "R300g" driver, which is the open-source R300 Gallium3D driver that supports the Radeon X1000 series, there is not much these days. The driver is effectively complete as far as the developers are concerned and the limited development manpower is focusing these days on the more recent ATI/AMD Radeon hardware generations. Via CGit you can see the R300-specific Mesa commits; there were a few R300g commits in May and April, but nothing too incredible.