I think that the release manager should update the version numbers, although if you change something like add a parameter etc, it is helpful to change d1 to d2 or a similar update for developers who are tracking CVS.
You should always increase the version number in the info file before tagging a package for openacs-*-*-compat for example. This makes sure that users who install from the repository get the latest version.
As this is the case, I don't think you really need to increase the version on _every_ commit. Just when the code in a consistent state. So I think you need to use your judgement here.
