Here are the slides from our class discussion of social media and web 2.0. You will need to click on the slide to move from one slide to the next. The embedded video clips show up as a still rather than a video since I don't think Keynote exports embedded video to a Flash file. If you need to review the videos, just google them - you should be able to find them easily.
If you are interested in learning more about specific social media technologies and/or Web 2.0 sites, check out this page which contains a self-running slide show of over 1,400 Web 2.0 sites.