Hi
http://digitizor.com/2011/08/10/fedora-16-no-btrfs/
"The Fedora developers have listened and have decided that Fedora 16
will not use Btrfs by default. The announcement was made by Josef Bacik,
Senior Software Engineer at Red Hat. Bacik, however, mentioned that
Btrfs is still being considered as the default filesystem for future
release of Fedora. The target release to have Btrfs by default has been
shifted to Fedora 17 now."
Rahul