Nice paper looking at the benefits and negatives of social networking. An interesting negative is ‘social resistance to change’: “Active social networking opens you up to being heavily influenced by others. In a way it subjects you to a new form of social conditioning. Once your network knows you a certain way, it may resist some of your attempts to grow and change.”
http://www.stevepavlina.com/blog/2009/11/social-networking-rethinking-productivity/