The nodes run a traditional LAMP stack, with Nginx sitting in front of Apache as a proxy for static assets and for SSL termination.
The machines provide all the necessary components to build on Magento, including support for running multiple PHP versions side-by-side if necessary ( see below for details). It is setup with different machines running different versions of PHP.
These dependencies are installed as part of the setup process using Homebrew and Homebrew Cask. This setup relies on Vagrant and VirtualBox (or VMWare Fusion if that's what you prefer) running on Mac OS X to power the virtualized developer environment.
