(See update below)
Hmm....what'd missing from this NYT story about two New York state legislators busted on corruption charges? Wait -- in most news stories, don't they identify politicians by political party? Let's see...this NYT story about a Congressional hearing today identifies Peter King as a "Republican lawmaker" a full paragraph before they get around to mentioning his name. Looking around...here's an NYT story about the death penalty in Illinois; it takes a while, but Governor Pat Quinn* is clearly identified as a Democrat. Those are both from the current home page...let's see, how about when Chris Lee resigned from Congress last month? Yup, in the Times, he was a "two-term Republican."
But these clowns are just random New York state legislators. In fact the current article up right now is revised with a spelling correct to one of their names, but still no party affiliation.
I think the evidence is pretty clear that most bias in the mainstream press is institutional (that is, caused by the way reporters do their jobs, or to the benefit of the interests of reporters, editors, and media companies) rather than partisan. But every once in a while some partisan bias shows up. Hey, NYT: let your readers know that these (allegedly) crooked pols are Democrats.
*Corrected: I managed to mangle this in the initial post.
Further update: they fixed it! Plain Blog gets action. Or something. Anyway, both of them are now identified as Democrats in the current version of the story.