Any social networking site can be dangerous. The best way to deal with this is to create an account of your own, and make your child add you to the friend list with full access. This way you'll be able to see what they're saying, and decide whether or not it could be dangerous, or inappropriate.
Make it easier for pedophiles to know where you hang out!
And they get 5 points for adding their house. 5 points is 5 points, ya know.
Then, some people like to use the shout-outs to say things that aren't always appropriate.
Yes, you can limit your information to friends, but then you take some of the intrigue out of the game. So why bother in the first place?