I suspect the polls showing a close McCain/Obama race are inaccurate to put it mildly. So many other polls show a large margin of discontent with the status quo. Either that isn't rendering into actual voter rebellion, or the close polls are (ahem) rigged.
Given Diebold's history, though, I expect a close outcome could be easily engineered.
First they make you think its close, then less people complain when Diebold does their thing. Wag that dog!!