There is a video of Clay Shirky giving a presentation entitled It’s Not Information Overload. It’s Filter Failure (ht @JDTwitt from Twitter) .  The part I found most interesting starts around the 12 minute mark, where he talks about privacy. 

He says privacy is merely about the control of outbound information.  Before the internet and social networks the inefficiency of information flow was a feature, not a bug, when it came to privacy.  It was simply hard to spy on people.    (This is the concept of practical obscurity.) 

We have now moved from that evolved system to an engineered system where we must consciously deal with and control the privacy of our information.  Our mind-set has not evolved with this change.  His view is that explicit privacy protection doesn’t work, and we somehow need to make the control of outbound information flow work on a filter basis.