I think it would be fascinating to correlate the graphs on this chart with events that took place during the campaign. Just off the top of my head it appears that Kerry's support began to erode about the time the Swiftvets ads came out and Bush took a clear lead after the Republican convention. The most recent trend looks very positive for Bush, but I can't read polls any better than I can predict the stock market. I have no idea why Bush is surging, but I 'm sure someone is smart enough to at least speculate intelligently about the causes.
I also have no idea why these things go up and down. Are there really that many people who are constantly changing their minds? Or are the pollsters just asking different questions? Beats me.