Nouveau has been in development for many years now, but it's still not close to catching up with the NVIDIA binary driver in serious competition. The latest GeForce 400/500 "Fermi" and GeForce 600 "Kepler" graphics cards have zero re-clocking support upstream at this point.
More of the same: Nouveau losing out to NVIDIA's binary blob.
The Reaction Quake 3 results were a bit surprising with a smaller margin by which the NVIDIA binary driver was winning.