I think it is time for me to issue an unconditional intellectual surrender to Cosma Shalizi. Watching Nate Silver and his now http://fivethirtyeight.com over the past two election cycles has convinced me that the Bayesian framework he throws around his model is a major obstacle to people's understanding what is going on.
What is going on is made up of three things:
Polling--that is, asking people what they think of the election candidates in a structured way.
Aggregation--so that you are not just using one sample of 1000 to assess the current mood of the electorate but instead have something like 1/5 of the sampling standard error.
Smoothing--imposing structure on the time series, both that it ought to be close to "fundamentals" and that it ought not to change too quickly.