In your minds eye, imagine each of the people I'm following with a similar graph. Then stretch your imagination a little more and envsion hundreds of millions of these relationships being created in just a few years.
Now, take fifteen minutes and watch this talk by Henry Markram; especially the part that starts around 4 minutes and 30 seconds in.
With Twitter we are beginning to build out a social neocortex. The implications -as we've seen in the Middle East- are mind boggling.