Wordpress - How can I update a wordpress plugin from a Git repository (github)

I wrote a PHP class that allows a plugin developer to incorporate updates from GitHub within their plugin. Here's a link for it -> https://github.com/jkudish/WordPress-GitHub-Plugin-Updater

Check out this plugin updater class for WordPress: https://github.com/jkudish/WordPress-GitHub-Plugin-Updater

I recently wrote up a post about deploying an entire WordPress site with a few custom plugins and theme to multiple servers using Capistrano. You could probably do the same for just the single plugin repo.

There's a bunch of good posts out there for the step-by-step details on getting Capistrano going for WordPress.