Short url: caseywatts.com/mediawikionheroku
Unrelated update: my book is out! Debugging Your Brain is an applied psychology / self-help book
How to get set up with Mediawiki running on Heroku.
Create Git Repo
Fork https://github.com/mediawiki/mediawiki (from the web interface)
master worked fine for me, but you might want the last stable tag?)