Thanks. I was unaware this existed. Looks like it was launched in 2011[1]. Somehow I thought that with their (presumably, from what little I've gathered over the years) complex infrastructure setup this would be hard or impossible. I wonder if they have an Enterprise team devoted to keeping up with a SaaS mainline and how much work they have to do, or if they made/make some decisions that make this (Enterprise) a fairly self-contained "it just works" sort of thing.

[1] https://github.com/blog/978-introducing-github-enterprise