I came across a great walk through of how to deploy your code from GitHub automatically
Having managed a large number of web applications derived from various code repositories, I see the value in this.
I used to write some pretty complex scripts to do this automatically with SVN across 20+ Amazon EC2 instances.
You can configure your EC2 AMIs to automatically update upon new instances launch. Great way to load-balance code.
I'm going to set this up for my 5+ wordpress installs, so that they get updated when Wordpress gets update.
Good to know how to do for the future, with my other web applications.