OpenSUSE 13.1 RC1 is shipping with KDE 4.11.2, Linux 3.11 + Lots of Btrfs fixes, Snapper 0.1.7 with Btrfs support, NGINX web-server support, BlueZ 5, and a lot of other new/updated packages.
Last month I wrote about openSUSE looking at switching to Btrfs for its next release. The openSUSE 13.1 Beta released in September had also encouraged Btrfs testing on new installations. In announcing 13.1 RC1, Btrfs won't be the default for this release (as expected) but it does indeed look like they may switch for the follow-on release. There's been more than 5,000 new Btrfs installations since the openSUSE 13.1 Beta 1 debut.
Btrfs testing on openSUSE 13.1 has found (and fixed) over 25 file-system bugs and the SUSE developers believe "btrfs should be a safe choice for openSUSE 13.1 users and a good candidate for default filesystem for the next release."
More details on today's openSUSE 13.1 Release Candidate 1 can be found via the news.opensuse.org announcement. A second release candidate is scheduled prior to next month's launch.