What's the difference between M5-pre1 and M5?
We always put out a "pre" before the actual Milestone. The pre is then deployed, and after about a weeks worth of "real life" testing if nothing goes wrong we just update all of the stamps and finish the documentation and call it a Milestone. If there are significan issues we put out a pre2. It is highly unlikely that M5-pre1 will differ greatly from M5 in more than upgraded versioning. "pre" means "preview" or "pre-release'.
We'll go to a more standard versioning scheme after JBCS 1.0.