There is Diaspora, if privacy is really what users want then, why haven't we seen a massive conversion to Diaspora?
While I agree that privacy is not "really what users want", the lack of a massive conversion to Diaspora is not indicative of anything. There was an article a week or two ago where an investor pointed out that Facebook is a natural monopoly. What they were talking about is basically that, now that most people are on Facebook, they're not going to pick up and walk out for another social network.
You might. Your friends might. But you post on HN, too.