There has been a lot of discussion of the massive data set that Pete Warden has been collecting from Facebook and the initial visualization of American groupings of people, based on their friends and other profile information. He's going to be releasing this data for researchers tomorrow - all geared around finding interesting patterns in a massive data set of hundreds of millions of users.
Of course, one of the first things that people outside the research community will want to know is what this data says about them - can it confirm what I already know or tell me something new? We'll have to wait and see what kinds of results and fun applications come out of the work.
But in the meantime, you can play with your Twitter relationships. In the ReadWriteWeb article about Pete Warden, The Man Who Looked Into Facebook's Soul, Marshall Kirkpatrick writes about some of his other side projects, including Mailana and the ability to draw maps of Twitter users - one of many applications that do variations on this - by frequency of @replies. And the first place I looked was my own network. I like that it shows connections between people I follow - using line thickness to provide indication of communication frequency. And then you can expand a view by double-clicking on a contact.
I poking around a bit, I can see cluster of my contact networks who represent Boston, Chicago, Knowledge Management. It becomes even more evident when I add known connectors from any of those networks. And there are other ways to analyze the data provided by Twitter, such as by location or words used in those conversations.