Just read an article about a young girl who had her facebook page hijacked because she did not logout when she opened her page in the Apple Store. Someone used the computer after her and posted dreadful malicious accusations about her family. Make sure your children know to log out when they access their pages outside the home. The article was on a womens site - www.womentalking.co.uk
Worth reading and passing on the warning to other parents and your own children.