This article in Slate points out that contrary to what the press or many people might think, Kerry's position on the war, at least the authorization for it, has been consistent:

The reason so many people are confused about his position, Kerry says, is because they interpret his vote, incorrectly, as "a vote to go to war." "It wasn't a vote to go that day. It was a vote to go through a process," to give the president leverage at the United Nations and to get the inspectors back into Iraq. Kerry emphasizes on several occasions that he's been consistent on this point. "I said so all along," he says, sounding irritated. "Every one of you throughout this knows I have said there's a right way to do this and a wrong way to do this, and the president every step of the way has chosen the wrong way."

Kerry's right on this one. From the beginning, he's been consistent, if complicated, on the meaning of his 2002 vote.

Okay...this may be a consistent position, but it's a dumb one.

Look, he voted to give Bush war powers. This isn't something you do lightly, and it isn't something you vote for without the expectation that the President will, you know, actually use them.

If Kerry wanted U.N. cooperation and an even more explicit resolution endorsing force to be a prerequisite for going to war, then he simply should have voted against, you know, authorizing the President to go to war until those conditions had been met. He talks about the vote as "leverage". Where? With whom? Was the vote of the U.S. Congress supposed to sway U.N. member states? Well...if it was, it didn't. And if Bush couldn't garner enough support in the U.N. for action with or without the leverage of a Congressional vote, then there simply wasn't enough support for attacking Iraq, was there? Even if you blame it on Bush's inept diplomacy, there wasn't the international support for the war that Kerry says should have been a prerequisite for invading Iraq.

So why the hell didn't he vote against it and say, "When the U.N. gets behind this, I'll vote to give the President the power to go to war...and not a day earlier."

That's what he did for the first Gulf War in 1991:

Kerry is wrong, however, that his 2002 vote doesn't contradict his 1991 vote. The first time around, Kerry expressly criticized the justification he would use 12 years later, calling it "dangerous" and "flawed." In 1991, Kerry said, taking the quote again from the Globe book, "This is not a vote about sending a message. It is a vote about war."

Isn't this pretty stupid and hypocritical?