I think I'm doing something close enough to your request that it might be useful to you.
I have a Jenkins job which I use to synchronize copies of the git-client-plugin from its official location on github to unofficial copies on bitbucket, assembla, sourceforge, and google code. That's not quite the same as what you're requesting, but I think it is very close. I use the technique so that I have testable copies on multiple providers, in case the authentication systems at one of the git hosting providers behaves differently than others.
One of the jobs is configured to push to a single repository after running a build and test cycle.
The other job is configured to push to three different repositories after running a build and test cycle.
I can share the config.xml definition of the jobs with you, or screen shots of the relevant portions of the configuration page for each of the jobs.