Chris Mason noted that with the Linux 3.14 merge window Btrfs pull it's "a pretty big pull, and most of these changes have been floating in btrfs-next for a long time."
The Btrfs changes for this next kernel release have properties work for inheriting attributes down on a per-inode basis, file-system information is now exported via sysfs, and there's lots of performance improvements. This pull also has code clean-ups and bug-fixes.
The tons of individual changes for the Btrfs feature pull for Linux 3.14 can be learned from the mailing list pull request. Hopefully this pull is an indication of more good things to come now that the lead Btrfs developers work at Facebook and the kernel's block maintainer also joined Facebook.