Interesting article on reader polarization:
"Bush at War" and "Sleeping With the Devil" are just two of the political books that have dominated the best-seller list of The New York Times in recent months. But according to Valdis Krebs, a social-network analyst in Cleveland, these volumes — the first a blow-by-blow account of White House deliberations in the aftermath of Sept. 11, the second an exposé of corruption and hypocrisy in American-Saudi relations — share an unusual distinction. They occupy a sparsely populated middle ground, rare titles that have been bought by people who generally tend to shop for much more partisan polemics...
Even with the bridging books, the average distance between the map's left and right clusters is still four links — or in network theory parlance, "four degrees" — Mr. Krebs said. Given that the clusters represent ideological extremes, he reasoned that if he expanded his book sample to include nonpolitical best sellers like "The Da Vinci Code" and "The South Beach Diet," the distance between left and right would be reduced. To his surprise, that turned out not to be the case, though what, if anything, this means he is not entirely sure.
"It's possible there is some book or video or CD that everybody buys that would bring the two sides closer together," he said. "But when I did a search using the top five best sellers at the time, it didn't bring the sides closer together."