About Commit privileges, using distributed version control system would help reduce the fear of commit.
http://www.python.org/dev/peps/pep-0374/#decision
http://www.python.org/dev/peps/pep-0385/
http://mail.python.org/pipermail/python-dev/2009-March/08793...
It also means that you can "screw-up" until you push (and as such can put things for review, etc... more easily).
This probably doesn't scale, but you could certainly do it for just the predetermined contributors.
Again, I'm not saying git isn't more convenient - it is; the point is that even git-using projects end up with a "main repository" to which only a small number of people can commit. Increasing the number of people with commit rights can be useful even when using git.
Spoiler: He has a 'circle of trust'. He pulls and merges commits from people he thinks are really smart and those people in turn pull and merge from people they think are smart.
From what I understand, a lot of the uncertainty isn't about committing, per se, but rather about changing the canonical repository.