I accidentally came across the blog-post Git-powered wikis improved - GitHub. And this particular paragraph caught my eye:
The new editor has the capability to support every markup language that GitHub Wikis support. If you’re a fan of Markdown, Textile, pod or RDoc, the function bar buttons (e.g. bold, italic, underline, etc.) will now work. We’ve even written brand new inline help for many of GitHub Wiki’s supported markup languages.
The language definitions the editor uses are JSON-based and easy to edit. If you’d like us to support a markup language that we don’t currently support, Gollum, GitHub’s wiki software, is entirely open source – fork our code and send us a pull request with changes that support your choice language.
I sent a quick patch for org-mode in the function bar, and it has been accepted. :)
If not anything more, I hope, at least a couple of curious people will explore org-mode and find it useful.