Jow Maller outlines a straightforward system for using git to manage code from development copies and branches through production. The fact that deployment to live is automated, but I'd be worried about broken or unreviewed code getting deployed unintentionally. I think the best way to prevent that is to have live be its own branch, and then pushing changes to the live branch once they've been reviewed, tested, and blessed.
While his approach doesn't require moving or redeploying the live site, I don't think that works when you're using Drupal. You'll want to track drupal core, sites/all, and your local site's folders in different branches, per this setup.
The key idea in this system is that the web site exists on the server as a pair of repositories; a bare repository alongside a conventional repository containing the live site. Two simple Git hooks link the pair, automatically pushing and pulling changes between them.
