The current Cornell Chronicle and the current issue of the journal Science discuss a paper by David Liben-Nowell and Cornell CS Professor Jon Kleinberg. (David is Cornell class of '99, and a former winner of the department's Prize for Academic Excellence given at graduation. He's now an assistant professor of CS at Carleton College.) Their paper appears in the Proceedings of the National Academy of Sciences and analyzes the spread of Internet chain letters, using them as a way to study the broader problem of how information flows through social networks.
The Cornell Chronicle article is on-line at
http://www.news.cornell.edu/stories/April08/chainletters.ws.html
The paper was featured by the journal Science in its section "Editors' Choice: Highlights of the recent literature", on-line at:
http://www.sciencemag.org/cgi/content/full/320/5873/156d