Honestly, some people have nothing better to do than make up Facebook rumors (and demand you repost them on your wall).
The message consists of the following text: On Friday, Facebook will become owner of the publishing rights of ALL your private photos. You need to make a simple change. Go to Account, then Account settings, then Facebook Ads (along the top), Ads Shown By Third Parties, Edit. Choose NO ONE from the pulldown then SAVE. Takes 2 minutes. And please SHARE!”
While Facebook has used the “you’re-opted-in” type of change rollout before, I seriously doubt they would make a change of this magnitude without informing users. In addition, if this were true, the tech blogs would be all over it. They’re not because they’ve seen it before. Yawn.
Facebook does not own the rights to your pictures, you do. By posting them to Facebook, you are allowing them to use them as they see fit. You still own the copyright, and can stop Facebook from using them by removing them from Facebook entirely. What you can’t control (as with anything else) is other people. If someone else shares your picture(s), Facebook has permission to use them. You should (as always) control your privacy settings.
If you still don’t believe it’s a hoax, check here: http://kev2.me/72 for more info. Or read Facebook’s Terms of Service.