I know - I've procrastinated long enough about posting on the missing WMDs.
My original reaction to the "Bush lied" crowd was to dismiss them with reference to (among others) this, this, this, this, this, this, and all the links in this item. But - as tempting as it is to dismiss the "Bush lied" crowd with a sneer - it's hard to improve on the following formulations of Stephen Hayes:

There are serious questions the Bush administration will have to answer:
*How did a forged document about Iraq's pursuit of uranium make it into the State of the Union address?
*Why would President Bush tell the world that "we have found weapons of mass destruction," when quite plainly we have not?
*Before the war, the administration rightly focused on interrogating Iraqi scientists about WMD. What are the scientists in U.S. custody saying today?
*Is it possible that some of Saddam's WMD have already been distributed to terrorist networks?
For some of the not-easily-dismissable allegations that the Bush administration exaggerated the threat from Iraq, click here, here, here or any entry on Eric Alterman's blog.
One of my biggest problems with the emerging "Bush lied" meme is the way it shifts, for convenience's sake, to encompass several different concepts and arguments. Here are my takes on two different concepts that are conflated as necessary by Bush opponents:
1) The fact that we haven't found WMD yet shows that our intelligence about such weapons' very existence was flawed or false.
2) The fact that we haven't found WMD yet shows that even if they existed, the threat to the U.S. was exaggerated by the Bush administration to build the case for war.
The first argument can be disposed of by reference to any one of the links cited above (about my initial reaction to the "Bush lied" crowd), which is why the most intelligent administration critic - Josh Marshall - opines that "I still have a very hard time believing Saddam doesn't have chemical munitions stored somewhere." The second argument is best formulated by Marshall:

The public didn't get sold on this war because Saddam had nerve gas, or botulinum or even anthrax. True or not, a lot of people believed that. (I believed it -- and I still have a very hard time believing Saddam doesn't have chemical munitions stored somewhere.) The public got sold on the war because the administration argued consistently and vociferously that Saddam was on the brink of amassing far more fearsome weapons -- particularly nuclear weapons ("We don't want the smoking gun to be a mushroom cloud") and that he had growing operational ties to terrorists to whom he might give these weapons or even some of his less threatening chemical agents.
It was fairly clear before the war that neither of those claims were true. Since the war it has become clearer by the day that they were almost certainly not true.
Those were the imminent threats that made the war necessary in March. No waiting for inspections, no building up of alliances, nothing. There was an imminent threat and countries respond militarily to imminent threats.
The only thing that's pretty clear is that there was no imminent threat. And there is a growing body of evidence -- much of which was known, frankly, before the war -- that the administration did everything it could to push the claim that there was an imminent threat using what was often very, very weak evidence.
(Emphases in original.)

I would argue very differently. The public got sold on the war because they bought into the worldview of the Bush administration shaped by 9/11. That worldview was based on a fear - I'd argue prudent, but reasonable people can disagree - of the unknown. We knew Saddam had all sorts of nasty weapons. We knew he had been trying to get nukes. And we didn't know what he had been doing since the inspectors were kicked out in 1998. The lesson of 9/11 is that what you don't know can hurt you, and that threats you thought were manageable may not be. The point of the Rice quote - "We don't want the smoking gun to be a mushroom cloud" was almost exactly the opposite of what Marshall asserts. It was based on the fact that we didn't know whether the threat was imminent or not. That unknowability was the point.
Think about it. What else was the point behind the controversy of the new doctrine of "pre-emption" in the country's strategy of national security? If the administration's argument was that Iraq was an imminent threat, what was the big deal about pre-emption? It was only important because it was not based on the certainty of an immediate threat. The Bush administration's arguments to the country were based on uncertainty about the threats. That is one reason why the country has not turned against Bush yet, even though the weapons may not have turned up yet.

(I welcome citations to polling evidence regarding my argument about what swayed the American people, either pro or con.)