I've been working on this book for some time, and it's fascinating.
Edited by Robert Latham and Saskia Sassen
I will have a review out by next week, as well as one for The Structure and Dynamics of Networks.
What's cool are some of the digital pictures you get when you explore networks.
This graph is of Recruiting,com, and it shows how interactions online are from the hub and spoke model, not one big interactive mash-up. The clustering effect should be obvious. if you understand this map, you understand how communities work.
Here's a url for a prettier map, compliments of Bruce Hoppe.