Ivars Peterson's column in Science News recently featured Cornell research on social and information networks.
The two related pieces of research highlighted were by Lars Backstrom, Dan Huttenlocher, Jon Kleinberg and Xiangyang Lan (presented at KDD 2006), and by Bill Arms, Dan Huttenlocher, Jon Kleinberg, Michael Macy and David Strang (presented at the 2006 Conference on e-Social Science).
See:
Ivars Peterson, "Mining the Yesternet", Science News, 28 Oct. 2006.
http://www.sciencenews.org/articles/20061028/mathtrek.asp