This article entitled “Facebook's Great Betrayal” is a bit out-dated now but a few weeks ago, users logging in to Facebook were asked to choose some new privacy settings – many of them ominously set to “Everyone”.
A lot of the success of Facebook versus other social networking sites was that it gave users such granulated control over who could see what information about them but now, in an attempt to catch up to Twitter and with Google adding “Real Time” search as a major factor in generating search results, Facebook has made another move that has rubbed a lot of users the wrong way including encouraging users to share more information publicly and making some information public no matter what the user wants (lists of friends, profile pictures, etc.)
Coincidentally, I'm reading “Accidental Billionaires: the Founding of Facebook – A Tale of Sex, Money, Genius and Betrayal” which gives some insight into the personalities that created the world's most popular social networking site.