I know that I wrote not too long ago that I didn't like the term "social graph" but the comments I got to that post educated me to the reasons why it's a good term. So I am using it now.
But where is your social graph? In Facebook or myspace or LinkedIn? Maybe. But mine is in a bunch of other places;
1) email - Xobni proves what I've always thought. My primary social network is my email address book. But it took a tool like Xobni to present it in that way. It is shocking to me that AOL, Microsoft, Yahoo!, and even Google have not done anything with this opportunity. It's enormous.
2) this blog - MyBlogLog turned me on because it started to build a social network around this blog. But since the acquisition by Yahoo! its been pretty stagnant. Six Apart says they are going to give me the tools to build this blog's social network and open it up via OpenID. That's a cool idea. Bring it on.
These are the three places where my social network exists most strongly. For many it is Facebook or myspace or Beebo or LinkedIn or something else. The truth is that no one platform holds our entire social graph.
So when Marc calls out to Mark to open up the social graph, he should in fact be calling out to every application that is social (isn't that every app Marc). Because technology has allowed us to capture our worlds, database them, and map them. And now it's time to build on that. The social web is upon us.