It's a new version of an old fake warning.

With all the wild rumours circulating about Facebook, it's sometimes hard to know what to believe. Will we start to charge people money to use our service? No. Do you have to copy and paste that scary legal message your friends are sharing? No, that's just a good old fashioned Internet hoax. But there are a few steps you can take on Facebook to protect your personal information, and we're more than happy to share.