The Project for Excellence in Journalism, which is affiliated with Columbia University, released their analysis of bias in news coverage. Here's an article.
"The war in Iraq
Using a similar methodology on 2,187 stories, the study found reporting of the conflict had slightly more stories with a clearly negative tone than stories with a clearly positive tone — 25% negative, compared to 20% positive. The largest number, 35%, had no decided tone and another 20% were on multiple subjects with no apparent tilt.
Newspaper coverage most closely mirrored that balance, while Fox had the most pronounced slant. The cable TV outlet aired twice as many positive as negative pieces about the war."