That stuck out to me as well. It's true. I think most are very aware of the non-privacy of Facebook, and act accordingly. There is a value in more personal communication, however, I don't think an ad-based social network can deliver it.
But we've had personal communication for ages now. That's email, IMs, Skype, etc. I wonder how many users just use Facebook for the sake of private messaging by now because the topics that fuel conversations between friends are often of private nature. Things not everyone has to know. I think that kind of defeats the purpose of a social network though.
