The lead Btrfs developer, who is now being employed by Facebook along with other Btrfs developers, quietly announced the release policy change a few weeks ago on the developers' mailing list.
At the time of announcing it he also called the Btrfs-Progs 3.12 release for use in conjunction with the Linux 3.12 stable kernel release.
Mason wrote on the mailing list, "The new idea is that instead of making the poor distros pull from git, I'll be creating tagged releases at roughly the same pace as Linus cuts kernels. Given the volume of btrfs-progs patches, we should have enough new code and fixes to justify releases at least as often as the kernel."
The Btrfs programs are maintained via this Git repository. While it was missing at first, Btrfs has had its repair tool / fsck support available since 2012.
For those curious about the performance of Btrfs from the latest kernel I do have HDD benchmarks and SSD benchmarks from multiple file-systems on the Linux 3.13 development kernel.