The New Heroku, Part 1 of 4: The Process Model & Procfile
blog.heroku.com
blog.heroku.com
We're even running things like Redis instances off of a similar codebase, albeit one modified so the >1 server case is different.
Edit: Oh, and of course we're not exactly as open and launched as Heroku are. Just pleased to see that other people think it's a sensible way to build this stuff!
http://devcenter.heroku.com/articles/how-much-memory-does-a-...