First of all, the Iowa caucus doesn't even decide anything. It is not a primary, and the outcome of the caucus doesn't decide any delegates, doesn't win you any states, and doesn't lead to anything tangible in the way of getting you elected president. This thing is just level after level of confundity. As best I understand it from reading the Wikipedia entry on the matter, the caucus determines local delegates, who then go and elect county delegates, who then in turn go to elect district delegates, who then select the state delegates. AKA, this process is useless.
Also the way the caucuses are run is a fucking travesty. In order to vote you have to take several hours out of your day and go to the meeting place. Then when it's time to vote you don't get to cast a secret ballot, instead you have to stand in a group with the people who all support the same candidate. And then in some other corner of the room are the people who support another candidate. So you could get mad peer pressured into casting your vote. Or you could just be a non-Goldman who doesn't like to stand out from the crowd and so you linger for a second and then get in the group with the coolest people in it or whatever. That shit is mad rigged.
Also, the result of the caucus doesn't exactly line up one to one with the eventual results of each party's nomination. Since 1972, which is apparently how long the media have been sucking cocks in Iowa, the Deomcratic winners have been: 1972-Uncommitted (more people essentially abstained from voting rather than pick a candidate. Good way to spend your two hours at the caucus, people), 1976-Uncommitted, 1980-Jimmy Carter (incumbent), 1984-Walter Mondale (eventual nominee), 1988-Dick Gephardt (Dukakis finished 3rd), 1992-Tom Harkin (Iowa senator, the other candidates didn't run in Iowa), 1996-Bill Clinton (incumbent), 2000-Al Gore (only other contender was Bill Bradley), 2004-John Kerry (after the Howard Dean meltdown)
The Republican winners have been: 1972-I don't know, apparently only the Deomcrats made a big deal about 1972, 1976-Gerald Ford (incumbent), 1980-George Bush Sr. (Reagan won nomination), 1984-Reagan (incumbent), 1988-Bob Dole (George Bush Sr. eventually won, finished 3rd), 1992-George Sr (incumbent), 1996-Bob Dole (eventual nominee), 2000-Dubya (eventual nominee), 2004-Dubya (incumbent).
All of this is confounded too by the fact that the Republicans also hold something called a straw poll in Iowa, which is an even earlier vote held in the previous year that sets the tone for the Republican caucus.
I lost something there in the middle, but my point is that this is essentially just a media exercise where nothing gets acoomplished unless you decide to scream like a chicken afterwards (Byaaaaaahh).