This release includes several SMP scalability improvements for Ext4 and XFS, complete removal of the Big Kernel Lock, support for per-cgroup IO throttling, a network device based in the Ceph clustered filesystem, several Btrfs improvements, more efficient static probes, perf support to probe modules and listing of accesible local and global variables, image hibernation using LZO compression, PPP over IPv4 support, several networking microoptimizations and many other small changes, improvements and new drivers. You can read the full changelog as well.