Btrfs has got into good shape and is proving its reliability (though last month Btrfs failed me on a production test system, but generally it's been a good experience in recent times and there's many daily Linux Git benchmark systems I have running with Btrfs at LinuxBenchmarking.com), with it now being used by default on openSUSE, etc. Earlier this summer though it was mentioned that Fedora isn't yet planning for Btrfs by default.
One of those at the time involved with RedHat/Fedora was Josef Bacik who is now part of the Btrfs team at Facebook. He's now commented that he's no longer pushing for anything actively in Fedora but he made some remarks about Facebook's usage. Here's the relevant part of the message he had just sent out (emphasis added).
I'm not interested in pushing btrfs into Fedora now. There is nobody to support it if things go wrong. If you want to use btrfs you can, or you can use Suse. We're finding and fixing things in our internal testing at Facebook, and the power fail testing stuff I added early this year has given me a lot of confidence in our ability to not lose all of your data due to some weird bug. In a few months we'll have switched over lots of our boxes onto btrfs so that will give us a pretty good way to keep track of stability in a production environment. After that I imagine it'll be good to go for Fedora, but that'll be somebody else's decision.Hopefully once Facebook rolls out Btrfs in a full-production environment, corrects any lingering issues, and shares their success story that other Linux distributions/vendors will be more comfortable defaulting to this file-system that's been talked about for years as the Linux competitor to ZFS. here while there are daily Linux kernel benchmarks with some of those systems using Btrfs over on our automated test farm of the daily Git kernel code at LinuxBenchmarking.com.