Let's do a CVS graph
There are two branches:
- Head(aka Trunk): Most of the experimental patches goes here, totally unrelated (well, after Aviary was Branched

) to the 1.0 Release. The development will go back to this one after 1.0 is released
- Aviary(aka Branch): the 0.9 Release and the soon-to-be-released 1.0 Release are based on this branch. Basically 1.0PR is not 0.9.4 since there are so many new features in 1.0PR compare to 0.9.3. But like what hemiola said, the version numbers are just there for people to see, so don't worry too much about it.