There's been a number of Mesa Git commits this morning concerning video acceleration within the Nouveau Gallium3D driver.
For end-users, perhaps the most noticeable change is that for the GeForce FX "NV30" series there is now X-Video Motion Compensation (XvMC) support. This pre-PureVideo NVIDIA hardware has XvMC video acceleration support implemented using the PMPEG
hardware block. The NV30 support came by this commit
Another commit allows for NV50 PMPEG to be forced
. There were also a handful of other commits pertaining to Nouveau video support for NVIDIA GeForce 400/500 "Fermi" / "NVC0" hardware.