When running the Doom 3 client there was not any performance difference going from the 2011Q1 to 2011Q3 state, but with the recently released 2011Q4 configuration there is a significant improvement. Doom 3 at 1920 x 1080 still is not playable with Sandy Bridge HD 3000 graphics, but with the 2011Q4 configuration the performance goes up by 27%. When enabling the RC6 support, which should be part of the default configuration by the time there is the 2012Q1 set, the performance is up by another 11%.
At the beginning of the year when Sandy Bridge was first shipping, the Nexuiz performance under Linux was a complete mess. There were rendering problems, frequent GPU hangs, and the performance was horrific. Going from the 2011Q1 to 2011Q3 configuration had shot up the frame-rate by 5.6 times. After moving from 2011Q3 to 2011Q4, the Nexuiz frame-rate was up by 58%. With the latest Mesa 7.12-devel + Linux 3.2 Git code there isn't any further increase in performance, but turning on RC6 does drive up the frame-rate by 15% and makes the open-source game nearly playable at 1920 x 1080.
Warsow v0.61 would not even function properly with the Intel 2011Q1 stack for Sandy Bridge, but was working with 2011Q3. When upgrading to the latest stable Intel graphics stack, the frame-rate increased by 27%. With the latest Git code, the performance is up by an additional 14%. However, at 1920 x 1080 the Sandy Bridge performance is just under 30 FPS, but with Ivy Bridge this should turn into a playable gaming experience.