In this recent post to Theme.fm they have a guide to deploying your WordPress site (or really any sort of PHP-driven site) with Capistrano. There's some WordPress specific bits in there, but it's a good overall guide to deployment with this handy tool.
I'm not a Capistrano expert (yet) and in this post I'll try to give you an overview how to set it up and how to deploy WordPress applications (websites) in seconds. We'll work with only one server today but the principles in deploying to two or more are pretty much the same.
He starts by introducing Capistrano and talking about some of the major benefits it can bring to you and your project (most importantly - simple deployments). The tutorial helps you install Capistrano and get it set up to work with your Github repository to pull the source. The WordPress specific bit has to do with configuration files and suggests an "if" check to see if there's local config first. Also included are the updates you'll need to make to the Capistrano config file and the commands to push the latest as well as rollback to your previous version.