A big new feature is the log-structured filesystem NILFS2, which we already discussed earlier on OSNews. NILFS2 also allows you to mount its snapshots in read-only fashion. There are more interesting filesystems in this release, such as preliminary support for NFS 4.1, EXOFS, and FS-Cache.
We also see work to make the kernel boot even faster by using fastboot, which scans storage devices in parallel to the rest of the kernel boot process. We can also add another architecture to the supported list: Microblaze.
The new kernel will find its way to your machine soon enough, but if you can't wait, then you probably already know where to get the source and compile it. Have fun!