I've recommended the Econ Talk podcast before, and I really mean it when I say that you guys have got to start listening to it. The host is a democrat for social reasons (he mentioned it briefly in one episode), but he is thoroughly rational economically. Politics are not a part of his commentary, only solid, dispassionate economics.
Anyway, he interviewed one of the higher-ups in one of the large polling organizations. This fellow tore apart a whole bunch of misconceptions about polling. There is no such thing as a "statistical dead heat," real scientific polls are almost never presented in the media, and these opinion polls we hear of in election years are commissioned by politicos trying to figure out how to position candidates. They were never intended to be used for manipulation of media consumers. That's entirely the work of news organizations.