I recently gave a talk at Gnubies: the New York City GNU/Linux group for beginners. The talk was aimed at complete beginners so it won’t have a lot of new information for anyone who is already familiar with the topics covered.
The talk discussed both Debian and Ubuntu and explored the overlap to introduce the concepts of Free Software philosophy that are important to both projects.
For those that are interested, I’ve posted the notes I used (I gave the talk without slides) for those that want to give their own talk in HTML and ReStructured Text source.