With Ubuntu 13.04 expected to use kernel 3.8 as the default kernel we can expect to benefit form the performance improvements that have made their way into the kernel this cycle.
You could say kernel 3.7 was rather disappointing for Radeon users. The need to wait for legal clearance before open sourcing code really slows down the rate of improvements. That's yet another example of the broken system holding back innovation.
Not everybody will see improvements either, and improvements won't be across the board but at least there is overall improvements, eh?
Maybe the recent new of various open source game engines is related to this upcoming performance improvements. More likely Steam for Linux is the source of these projects' motivation, but if I can play Morrowind natively on Linux without using Wine that's a huge improvement in and of itself.
Heck, I wouldn't even mind replaying IceWind Dale II on Linux sans Wine.
2013 is looking to be an interesting year for Linux gaming indeed...