Snopes.com explains all of this quite well:
Facebook users cannot retroactively negate any of the privacy or copyright terms they agreed to when they signed up for their accounts, nor can they unilaterally alter or contradict any new privacy or copyright terms instituted by Facebook, simply by posting a contrary legal notice on their Facebook walls. Moreover, the fact that Facebook is now a publicly traded company (i.e., a company that has issued stocks which are traded on the open market) or an "open capital entity" has nothing to do with copyright protection or privacy rights. Any copyright or privacy agreements users of Facebook have entered into with that company prior to its becoming a publicly traded company or changing its policies remain in effect: they are neither diminished nor enhanced by Facebook's public status.
If you do not agree with Facebook's stated policies, you have several options:
So, we can all go back to recipes and shared eecards. And, frankly, that's OK. Happy Facebooking everyone.