bbPress is already at the latest stable version (2.5.8) and works great. There are some issues with WP 4.4 (mainly for hidden/private forums) and I’m waiting for WP 4.4.1 like many others, but the issue is there, not in bbPress.
The lastest info I have is that it should be available before Mid January, but that’s just unofficial data.
If you are referring to bbPress 2.6 (nothing to see with WP issues) then I can tell you that tests are fully ongoing (well, a bit less in the last week, but everybody deserves some rest), so I do hope that shortly 2.6 will be out also. You can already test the alpha development version here.