BlogPulse has published a paper on the

BlogPulse has published a paper on the Political Blogosphere and the 2004 U.S. Election. “Liberal and conservative bloggers also had clear preferences for mainstream news sources that they cited. Fox News (89%) and the National Review, (92%) for example, received most of their links from conservative-leaning blogs. By contrast, 91% of Salon.com’s links came primarily from liberal-leaning blogs.”