At etech 2006, danah boyd gave what Kathy Sierra called an astonishing talk.  It ended with this definition of an intriguing problem.   Is anyone aware of any solutions to this problem going public in the last year or even in the near future?  

Provide the cultural environment where people can accidentally connect with strangers over meaningful things without being forced to face everyone on the system. Let users privatize or wall off access to only certain people for their own needs. Let users see the values of being public. Of course, balancing privacy needs with public possibilities with the lack of interest in dealing with the *whole* public is quite tricky. Anyone who can solve this design challenge with a robust system will win the hearts of users and investors.