A bot could subscribe to the list and create branches in a public repo.
(This idea feels familiar -- didn't somebody attempt this already?)
Thomas Rast maintains git notes that link git commits to their gmane
discussion, you can get them with
[remote "mailnotes"]
url = git://github.com/trast/git.git
fetch = refs/heads/notes/*:refs/notes/*
There is gmane branch and a message-id branch, its pretty usefull.