Fedora is targeting the addition of Btrfs as the default file system for their upcoming Fedora 16 release. Exciting news indeed. Checkout the following links for more information:
http://digitizor.com/2011/06/09/fedora-16-btrfs/
http://www.phoronix.com/scan.php?page=news_item&px=OTU0Nw
http://fedoraproject.org/wiki/Features/F16BtrfsDefaultFs
