I think the The Economist does a nice job describing the state of social networking and its future fate:

Online social networks | Everywhere and nowhere | Economist.com

In the end, we’ll just all have a blog, without a need to have an account on any specific system. Our patients will have one too. This doesn’t mean everything will be an open book, just that we will be on one open-source platform that communicates in some fashion via RSS. The fun part will be connecting those life experiences to the right people at the right time. In Health IT, I think it will be very advantageous for a patient to consent to share aspects of their life experiences with their doctor. This is very consistent with the chronic care model.

And I deleted my LinkedIn account, too.