With Warsow, using the Intel SNA architecture did increase the average cross-resolution frame-rate for this Qfusion-powered OpenGL game by 12%. The latest Windows driver, however, was still faster than Linux by 6%.
The latest Intel Windows driver has managed to edge-out the latest Linux driver in terms of OpenGL performance for common software. However, the Intel Linux driver is still poised to be boosted by the "Sandy Bridge New Acceleration" architecture that is not yet the build-time default. From the testing today, that is still not to toss the lead back in the favor of Linux, but it is a very close race. The Windows driver also has the advantage of supporting OpenGL 3.x where as Intel and Mesa still don't have full support yet for even the OpenGL 3.0 specification, along with other long-standing limitations like not being able to enable S3TC texture compression support by default.
We will see what happens in terms of Intel SNB driver optimizations for both platforms in the coming months. It will also be interesting to see how both platforms compare once Intel releases the "Ivy Bridge" hardware late in the year. Intel's Open-Source Technology Center team responsible for the Linux driver stack has already been working fiercely on Ivy Bridge support, so there it may be an interesting friendly battle as well.
In a few days on Phoronix are more Intel Sandy Bridge benchmarks (from a Core i5 2500K) using the latest Linux Git code and comparing it to the Nouveau (NVIDIA) and Radeon (ATI/AMD) open-source drivers with a few different graphics cards.