An Encrypted Social Network

Or is it for non-technical users who are paranoid about Facebook privacy, having ready something about it once? In which case, wouldn't some kind of encrypted privacy overlay for Facebook be more helpful?

It just seems painfully, painfully niche. I can't see how it could overcome both the traction problem that all social networks face (i.e., reaching critical mass - people are only on social networks because other people are there), as well as convincing people that this is something they need (existing social networks will try hard to convince people they do not need anything like this, because their privacy is already safe). Seems a very hard sell to me.