There's a great piece about Keith Olbermann at The New Yorker, talking about the issues he's had and the success he's gained from being both unashamedly honest about his opinions and willing to publicly antagonize people like O'Reilly.
Best bit? Probably when he was called into his bosses' office after submitting a script telling Pres. Bush to "shut the hell up." When asked why he'd use that phrase, he said "because I can't say 'shut the fuck up' on-air". The line stayed in.
(Also, the man can't drive for medical reasons, and hates to fly. One of your more immobile journalists, then, and even more surprisingly good for that.)