To help us manage the considerable volume of open issues in Jira I've added a few placeholder versions that I'd like us to start using to schedule existing as well as new issues the we don't expect to be able to resolve in the upcoming release of 4.2. The differences between the versions are in the type of compatibility they provide.
They placeholder versions I created are: 4.2 Upcoming release scheduled for September 2007. 4.2.1 Expected first patch (forward and backward source and binary compatible) release for 4.2 scheduled sometime later in 2007. There may be other 4.2.x releases after this one or there may not, depending on how things go. If there are, they will all provide the same degree of compatibility. 4.3 Next minor (forward source and binary compatible) release after 4.2 (may never happen). There may be 4.x releases after this one that will all provide the same degree of compatibility. 5.0 Next major release, tentatively scheduled for December 2008. This is a binary and possibly source incompatible release that should have most of the TR1 stuff in namespace std. The definitions of Forward and Backward compatibility I'm using and the versioning policy are outlined in the draft compatibility and versioning policy I just uploaded.