It is interesting that concerns over data privacy etc. aspects of Facebook and other social networking sites seem to be global. Lyn Parker and I have given a couple of sessions on "What does your Facebook say about you?" at Sheffield University (see http://cilass.group.shef.ac.uk/?p=267) and there was quite a lot of interest around this topic from all parties. I'm in Australia at the moment and in yesterday's newspaper there was an article reprinted from the Washington Post:
Hart, K. (2008) "Face like an open book." Sydney Morning Herald. The guide section. 23 June, 10.
It mentions studies by people in the US, including a study by Adrienne Felt at the University of Virginia who looked at 150 popular Facebook "applications" and found that the majority "have uneccessary access to private data". More info on her study is at http://www.cs.virginia.edu/felt/privacy/