I find this hard to believe. From what I can see a typical poll has a (statistic and systematic) uncertaincy of at least 2-3% (absolute, not relative). This means that in many states it is in principle impossible to make reliable predictions and due to the very non-linear "the winner takes it all" system, these uncertainties become amplified when it comes to the majority in the electoral college.
From 2000, we still remember that it is not the total number of votes (assuming there are no further problems in deciding which ones are valid) that determines the next president but also how they are distributed over the country. And none of the reports on recent polls that I have seen comment on this. They all state only that Bush is leading by a couple of percent but not how that translates into votes in the electoral college.
Talking of conspiracy theories, there is still the issue of Bush being radio controlled during the TV debates. I must say, I would prefer if he would have been. In the end, it is also his advisors that determine policy so why shouldn't they have their say in the debate? Bush by himself is probably not very powerful or influential, it is the people in the background that you never get to see because they are hiding in their think tanks and operate the teleprompter or the RC for the president's mouth from there. And they make sure that groups that put huge sums of money into getting candidate x elected get their money's worth of their investment.