GitPHP-glip is fork of GitPHP that uses glip library instead of exec() calls, so you don’t even need to have Git installed on a server.
This is useful is you want to host Git repositories on PHP-only hosting.
It supports pushing to server using “HTTP smart tranfer” protocol. You need Git 1.6.6-rc0 or later to do this.
Example of git-push command:
git push http://hostname/gitphp/push.php/repo