To some surprise, Eric Anolt then fired up Left 4 Dead 2 running from his Linux laptop using the Intel Mesa DRI driver. It worked! There was the one rendering bug, but the performance was reasonable. The experience isn't completely fluid, but it's playable on the open-source Intel Linux graphics driver.
Eric was running the latest open-source Intel Linux graphics driver code -- kernel and Mesa. He was running what's effectively Git master, building it with the patented texture-float support for floating point textures, and using the external S3TC texture compression library. Again, the L4D2 performance is playable with the latest Intel hardware on the latest code, but further performance improvements will arrive in the coming months.
While not the focus of this Intel presentation at the 2012 GStreamer Conference in San Diego, there's likely some wondering now about the open-source Radeon and Nouveau (NVIDIA) drivers with Valve's games on Linux. Months ago I did put Valve in contact with Nouveau and Radeon developers, but there isn't any active communication with those camps at the moment. This isn't entirely surprising though since the official AMD developers working on the open-source Radeon Linux driver have a hard enough time working on hardware support for GPUs that were released the better part of one year ago. On the Nouveau side they're all community-based and resources there are also stretched thin with working on OpenGL, new hardware enablement, etc. NVIDIA and Radeon hardware also has the respective binary graphics drivers to complement the open-source drivers -- which are much faster and provide much better OpenGL compliance -- while on the Intel Linux side there's only this lone open-source driver.