When talking about the state of Fedora 13 features last week following our early Fedora 13 benchmarks, the Btrfs system snapshot feature was marked as being 0% complete. However, the Fedora 13 feature list has been updated and this feature is now deemed 80% complete.
The SystemRollbackWithBtrfs page mentions that patches for listing sub-volumes and setting default sub-volumes have been submitted to the Btrfs mailing list and that these patches, which are needed for this feature to work, should end up reaching the inbox of Linus Torvalds within the next two weeks. Hopefully this work will get pulled into the Linux 2.6.33 kernel, albeit it's quite late into the development cycle.
Besides the Btrfs patches, a yum plug-in continues to be worked on that automatically calls upon Btrfs to create the file-system snapshots. What has not been started yet is the Palimpsest code for handling the Btrfs snapshots, but that's simply being postponed until the aforementioned Btrfs patches are found within Fedora's Rawhide kernel.
It looks like this feature should end up making it in time for Fedora 13, but it won't be of benefit to many until the Btrfs file-system is used by default within Fedora, which still may be a ways away.
Besides updating the Btrfs system rollback status, the implicit DSO linking, NFSv4 support by default (now 100% complete), NFS client IPv6 support, and DisplayPort support for the Nouveau driver features have also been updated.