The developers of Crystal Space, an open source 3D engine, announced a pseudo-stable release recently:
The latest stable release (0.98r004) is getting old. More and more I have to tell people to use the latest CVS because bugs have been fixed there and CVS is simply a lot better. On the other hand many people are afraid of the instability and indeed from time to time the CVS version doesn’t compile or work properly. So normally it would be time for another release. The next stable release is supposed to be 1.0 but we are not ready for 1.0 yet. A lot more work has to be done still. So we decided to have more regular intermediate pseudo-stable releases. These pseudo-stable versions are not as well tested as the real stable release but we are pretty confident that they are okay and most things are working properly.