The Implicit Social Graph - Whats its value?

I like Fred's example of people with similar music taste on last.fm. I like the idea of being connected with people who will attend the same event as me, or an event I wish I was at, or whose netflix ratings correlate highly with mine.

I would imagine that eventually, the explicit side of things will more be addressing the privacy issue you mention. But really, I want my graphs to be generated for me with the least work possible.

Instead of a social dating site, what about an implicit social graph approach: show me people in this coffee shop who are open to being approached for a brief chat. Show me people in this city who are willing to grab a beer with a stranger in town for the night who have similar interests.

Lots and lots of interesting stuff will become possible as we start to master all the information and implicit connections available out there even today.