She presented some counts of stories and pictures, like "the number of Obama stories since November 11  was 946, compared with [John] McCain's 786." But she noted that much of this disparity was because of Obama's longer primary fight. Looking at the race since Obama captured the nomination, she had some less striking stats, e.g., "Counting from June 4, Obama was in 311 Post photos and McCain in 282."
She found bias on the opinion pages too:
The op-ed page ran far more laudatory opinion pieces on Obama, 32, than on Sen. John McCain, 13. There were far more negative pieces about McCain, 58, than there were about Obama, 32, and Obama got the editorial board's endorsement. The Post has several conservative columnists, but not all were gung-ho about McCain.
Blogger Matthew Yglesias (11/10/08) described this as a "call…for less intellectual honesty on the Post's op-ed page," and he's got a point. It's not clear what the point of an opinion page that would praise and condemn every politician in equal measure would be; you might as well just print the slogan "six of one, half a dozen of the other" and save yourself the effort.
The only really substantive passage in Howell's finding of pro-Obama bias in the Post was this paragraph:
Obama deserved tougher scrutiny than he got, especially of his undergraduate years, his start in Chicago and his relationship with Antoin "Tony" Rezko, who was convicted this year of influence-peddling in Chicago. The Post did nothing on Obama's acknowledged drug use as a teenager.
Actually, the Post did a front-page, 1,250-word article on Obama's use of drugs (1/3/07), but that was before Howell's survey period. During her survey period, I count at least 11 mentions of Obama's adolescent drug use (e.g., 12/14/07, 8/24/08, 10/10/08); it's not clear how many times it would have to be brought up before it would count as more than "nothing."
A Nexis search for "Obama and Rezko" turns up 54 stories in the Post during Howell's survey period. That seems like an awful lot, actually, given how little substance there really was to the Obama/Rezko "story."
And "his undergraduate years" and "his start in Chicago" needed "tougher scrutiny"? I think it's hard to make a case that what's missing from election coverage is more muckraking of the candidates' college years.