The btrfs is a new Linux copy-on-write filesystem that will replace ext4. As the author of ext4, Theodore Ts’o agrees this is the right direction. The new filesystem is pronounced as either "butter F S", "better F S" or "B-tree F S".
The main site is hosted by kernel.org.
The biggest problem I heard about was that a user space tool was missing, however that was released in Feb, 2012 for use by sysadmins and Linux distributions.
Two distributions support it right now, Oracle (where btrfs is developed) and openSUSE. This Chris Mason video recorded April 2012 provides a current overview of the filesystem’s status.
We hope you have enjoyed our regular meetings at Bobby G’s in Berkeley on the second and fourth Sunday of each month. Our next meeting is May 27th. We also talked to an incredibly fun group of faire goers about Bay Area Linux all weekend at Maker Faire May 19th & 20th.