As tptacek says, this is a transitive trust issue. The problem is that Facebook doesn't seem to care about the security of your data (facebook considers your da

As tptacek says, this is a transitive trust issue. The problem is that Facebook doesn't seem to care about the security of your data (facebook considers your data to belong to them) and is unlikely to enforce security requirements on sites it partners with. If they ever open this up for general use, I hope sites like http://youropenbook.org/ http://youropenbook.org/ sign up. I can certainly see this being abused on a massive scale.