While some having been thinking that Fedora developers might enable the Btrfs file-system by default in Fedora 22, that doesn’t appear to be the case. Fedora is unlikely to see Btrfs by default until at least Fedora 23.
OpenSUSE 13.2 Beta 1 is using Btrfs by default as the first major tier-one Linux distribution using the next-generation file-system along with SUSE Linux Enterprise.