Things You Might Want to Avoid Posting on Myface #1

Am I the only one who has seen those little invites to join groups that have titles like "Joe and Buffy are getting married!"? I've noticed that often they are set so anyone can join. They also often seem to be "open" meaning anyone can read the wall. If that's true, why would you post your full address on the wall? I know you want an invitation, but really? Are you new?