Last week I gave a short talk at the Seattle PHP User Group. This meeting: http://www.meetup.com/seaphp/events/197182452/
The topic was contributing to open source projects. We had a talk from Jeremy Lindblom about how to do a pull request and other basic tools, and a talk from Kris Craig about contributing to PHP itself.
I tried to illustrate how the issue/patch process works on Drupal.org. Not sure how well I succeeded. :-)
Here's my Google doc my slide deck for any who are interested: