Linus Torvalds writes in the release announcement, "It's a new year, people are getting back to work, and trying desperately to forget the over-eating that has been going on for the last two weeks. And hey, to celebrate, here's -rc2!"
Linux 3.8-rc2 is fairly small in terms of changes for being past the merge window. The big item for this second release candidate of the Linux 3.8 kernel is the DRM/GPU updates, namely the extra Nouveau features that merged late. There's also some file-system updates, ARM OMAP clean-ups, and various other work to be found in Linux 3.8-rc2.
If you're not familiar with this kernel that's shaping up to be amazing, see the feature overview for the Linux 3.8 kernel.