Conservatives stupider than liberals? Well, this study pretty much proves the opposite. What kind of numbskull would be impressed by this? The obvious explanation--that Bush won over a lot more voters this time around--is unbearable to these guys, so they come up with a nutzo hypothesis that turns Bush's victory into a scam. Some people will go to any lengths to avoid reality.
You've put your finger on a core inconsistency I've found in liberals. On the one hand, they believe that conservatives (or anyone else who does not agree with them) are fundamentally stupid. If they were only brighter, they would see the error of their ways, they would agree with the "progressive" liberals.
This extrapolates to "Bush is stupid," "Red state voters are stupid," and most recently, "Condoleeza Rice is stupid."
On the other hand, they attribute the most devious, manipulative behavior to the conservatives. "Bush stole the election again," "we really went to Iraq for oil," "they got the marriage amendments on the ballot to bring out more voters for Republicans," "the world is controlled by Halliburton," "the Republicans deceived the voters into thinking the election was about values," etc.
The bottom line is the Greeks had a word for it: "hubris." And just like the Greek tragedies, hubris has been the downfall of the Left.