When people mock the Facebook share price and question their long-term sustainability, remember that they're in a position that no company has ever been in before. They are trying to monetize personal data that has been provided willingly. They'll always be walking a fine line of giving their users what they'd like and giving their customers what they'd like.
This is just Facebook trying something that is entirely consistent with their philosophy and historical trend.
Look at gmail, for example. How do they "monetize personal information"? Or look at twitter. If I set my account to be protected (which I do) then I have a modicum of security in knowing that my personal messages won't be viewable by the entire world without me knowing about it.
It's not that difficult to get the basics of privacy right. Many companies do it just fine. The difference is that facebook doesn't care.
This is just Facebook trying something that is entirely consistent with their philosophy and historical trend.