Gitblit offers an API that should permit you to list repos easily enough: http://gitblit.com/rpc.html

It seems pretty trivial to use, e.g.: https://git.centos.org/rpc?req=LIST_REPOSITORIES

You should be able to use that to clone all of the repos and then use some combination of 'git fetch' and 'git log' to get the activity logs.  Or use the RSS feeds for each repo, if you prefer.  TIMTOWTDI.

This seems like a significant improvement, since you no longer have to diff the ftp 'ls' output -- there are actual machine-consumable feeds and APIs to use.