Since it isn't clear from the article: Is this "git deployment" just for the code components of WordPress (e.g, core upgrades, themes, and plugins), or does it cover content in the database as well? The latter would be much more interesting and useful.
We're recommending that core not be part of the deployment, since that could conflict with normal versioning of WordPress. It covers files and database. Check git.wpengine.com for the super in-depth coverage.