Antony Mayfield has written a good, clear introduction to the social media phenomenon. It’s available as a free ebook from Spannerworks. (Via a Kami Huyse digression.)
Victoria should find this useful. She’s a PR student at another university, but her message grabbed my attention because it named two people we both know. Social networking in action.
PR Studies 
Glad my digressions are sometimes useful to others 😉