It should be noted that the methodology here was a bit different from most polls. The poll respondants were asked who they supported, but were not prompted with any list of names of candidates, so they had to volunteer the names on their own. Whether that makes it more or less accurate is up to you to decide.
This poll seems not out of line with other recent polling, maybe more on the Republican side than on the Democratic one. Iowa is Clinton´s weakest state as we know, besides the obvious disadvantages she enjoys in the states of some favorite sons (IL, NC and NM). Obama can still win IA, but is it enough of a boost for him ? He needs to at least improve his poll numbers in SC as well. On the GOP side, I have no doubt that Romney will win IA and that Huckabee may finish second, Thompson third. As for the methodology, I think candidates who already aired TV ads are slightly favored in this poll (->Romney), but as I said, the poll seems not really out of line.
A win would be massive for Obama in Iowa especially considering it is a lily white state. I imagine that he would surge in NH after as Kerry did in '04. As for SC, does anyone know what is going on there? I haven't seen a new SC poll in over a month.