Думаю, что собществу будет любопытен и полезен материал:
Giant Global Graph 
So The 
Graph word has been creeping in. BradFitz talks of the 
Social Graph as does Alex Iskold, who 
discusses social graphs and network theory in general, points out that users want to own their own social graphs. He alo points out that examples of graphs are the Internet and the Web. So what's with the 
Graph word?
И далее, 
What I mean by "social graph" is a the global mapping of everybody and how they're related, as 
Wikipedia describes and I talk about in more detail later.