From Law Technology News: "How Facebook Can Make or Break Your Case," by Eric B. Meyer--
The first thing I do after I receive a copy of an employee-filed complaint -- before I read the complaint -- is check the plaintiff-employee out on Facebook and other social networking sites.
I print any information that employee has made publicly available. I save any pictures the employee has published online and I send a list of the employee's friends to my employer-client to cross-check against a list of current and former employees. I do this because, generally, a Facebook user will allow friends greater access to online content.
According to Meyer, "If your client is sued by an individual and you are not harnessing the power of social media as part of your litigation strategy, you're making a BIG mistake." (Link from Future Lawyer.)