On May 20, 2007 I gave a presenation at RailsConf on Laying Tracks: How to Contribute to the Ruby on Rails open source project. Here are the slides from that talk.
These slides are made available under Creative Commons license Attribution-NonCommercial-ShareAlike 2.5. That means you can do what you want with them as long as you don't make money off it and give me credit for my work.
The slides: Laying Tracks