Two things to keep in mind:
1. The media outlets all declared the Wisconsin Recall was too close to call, and we all know how that turned out.
2. The polls showed Kerry up in Ohio by 5 points in the days leading up to the 2004 election, and Bush won Ohio.
Which makes me think the Marist poll’s finding for IA could be off; they do reveal that Romney is very likely ahead in NH and WI and he’ll win both states Tuesday!