Hugh Macleod has a great post that helps explain what is at the heart of the social networking phenomenon, namely the social object.

It can be anything that arises passion in people. Sports, technology, a cause, whatever. People gravitate towards the object (the node) and then the network forms (and hopefully, the network effects take off)

So, coming back to the oft-cited idea of the "raving fan," the marketing challenge for Microsoft (and our partners) is

1. are we social objects around which people organize? I dare say, yes.
2. what are we doing to foster the social network around us as objects? I dare say, very little.

At least now we have an idea of where to focus our efforts (I hope).