It was supposed to get into 10.10 for testing but according to the blueprint it was deferred (https://blueprints.launchpad.net/ubuntu/+spec/foundations-m-btrfs-

It was supposed to get into 10.10 for testing but according to the blueprint it was deferred (https://blueprints.launchpad.net/ubuntu/+spec/foundations-m-btrfs-support https://blueprints.launchpad.net/ubuntu/+spec/foundations-m-...).