I think this tutorial is a treasure. It's a great introduction to the entire rails ecosystem, including TDD, git, heroku, and the like. I went through the 3.0 version a while ago, but so slowly (as in, a chapter every couple of weeks) that I forgot a lot of it. To those like myself, working through this in your off hours, I recommend keeping Anki (or equivalent) open and adding notes as you go.