Although it almost certainly comes too late to have an impact on the Iowa caucuses,, the recent specificity from John Edwards on the role of Americans as "trainers" in Iraq is actually very significant. While Iraq has been less of an issue in the primaries due to broad intra-party agreement on the issue (with Democrats wanting to end the war and Republicans wanting to continue it, generally speaking), the role of U.S. forces during the draw-down -- which could last quite some time -- has not been discussed or debated in detail. I believe a significant training mission in Iraq would be profoundly counterproductive for the U.S. (an opinion that is partially informed by my occasional work with Iraqi forces when I was in Baghdad for half of 2005), but there are plenty of Democrats who continue to support such efforts.
The problem with training the Iraqi army is, in brief, twofold: First, it essentially serves to prepare one side of a civil war; as Edwards said, we are propping up their bad behavior. The government forces are largely made up of -- or at least infiltrated by -- Shia militias, and they are more loyal to the leaders of their group or sect than to the central government. Second, a prolonged training mission extends our physical occupation of the country, perpetuating the colonialist imagery (and impact) that Iraqis abhor. As far as I know, Clinton and Obama continue to support (or at least have not explicitly repudiated) some training mission, though that would obviously be reduced or eliminated as forces are redeployed based on their plans. Still, even at this late stage of the primary campaign, it would be helpful and instructive to have the question of troop role -- and not just number -- discussed by the major Democratic candidates.