I want to follow up on Cass Sunstein's post about ideological amplification. It reminds me of a study I read about a few years ago by Valdis Krebs, a network theorist, on the polarized political reading habits of Americans. (I see he's updated the study for 2006). Using the Amazon "Customers who bought this item also bought..." feature, he found that people who read Ann Coulter weren't reading much of Michael Moore, and vice versa. The few books that found audiences of diverse ideological persuasions were those by straight news reporters like Stephen Kinzer, Tom Friedman, and Bob Woodward.
So my question is this: could self-reinforcing trends be pushing all of us into ideological echo chambers that move us to the left or the right? Cass worried about the Internet's contribution to this phenomenon in Republic.com. How much is the political polarization we sense around us today comes from increased Web and blog reading? Can Open University be a corrective?