Leszek Godlewski, the Linux developer who dealt with the port of Painkiller: Hell & Damnation and has presented on porting games to Linux, gave some interesting driver recommendations.
Leszek wrote yesterday on SteamCommunity.com, "After some additional internal testing, I've decided to revise my statement from the release notes and actually advise open-source drivers for non-NVIDIA GPUs, especially if the proprietary ones crash for you. ;) Thank you, guys, this is directly because of your beta feedback!"
In other words, if you're running NVIDIA GeForce hardware use the proprietary driver but for everything else use the open-source Mesa/Gallium3D drivers. This isn't too much of a surprise given NVIDIA's first-rate binary driver status while the open-source Nouveau driver has a major limitation right now of no proper re-clocking support to deliver good frame-rates. For AMD Radeon hardware, the Unreal Engine 3 game is preferred now to use the Radeon Gallium3D driver over AMD's controversial Catalyst driver. With Intel hardware there's no option as there's only the single open-source Linux graphics driver for their hardware.