gitup is a multi-server deployment tool based on git. Pushing to a git master will cause all of the clones to update their working copies and restart.
To run a master (where you push your git repos), simply fire up a gitup server on an internet facing box.
gitup --port 3000 --secret foobar --git-user foo
You can now push to this server from your project directory via git:
git push http://foo:foobar@hostname:3000/repo-name master
A clone is another server which will keep the git repo up to date based on the master git repo. Whenever you push to the master, the clones all update.
gitup clone http://user:pass@hostname:port/repo dest