You might be thinking: "But... I have privacy settings that would prevent anyone except my friends to see my photos." These privacy measures are not nearly as effective for several reasons. First, you might actually be a friend of a friend of defense counsel. If you have used Facebook, twitter and other networking sites long enough, you know that the world is actually that small. Secondly, the opposing counsel can try to "befriend" one of your friends in order to get access to your information. Many people confirm random friend requests just to be nice, so one of your friends might fall into that trap. Lastly, the courts approved subpoenas for social networking activity in the past, if it was relevant to the subject litigation.
So, if you are involved in litigation, make sure you "clean up" your online social networking life before your attorney files a lawsuit and the other sides starts searching for information about you on the internet, because be assured - they will.