If Keith Olbermann were not a very real, very angry American news anchor, commentator, and sportscaster, then he might have been a character dreamed up by the brilliant screenwriter Paddy Chayefsky in the movie “Network” (1976), his searing satire of television news. In that movie, an anchorman named Howard Beale goes insane, chucks his professional impartiality, and starts ranting and raving on the air against the depressing state of the world. As the host of the nightly newscast “Countdown with Keith Olbermann” (MSNBC, 2003- ), Olbermann’s critics – and some of his fans – would argue that