Although you should never make too many assumptions in Iowa most current polling suggests that the winner in Iowa will be either Romney or Paul with Santorum likely to come in 3rd.
My guess is that Romney will come out on top because the latest polls seem to suggest that the undecided are not ideologues but pragmatists wanting the candidate who can win. Given a choice between Romney and Paul I expect those voters to shift to Romney.
Weather is also a factor to consider and while it is hardly going to be warm and toasty tomorrow the reports do suggest a relatively warm and dry evening. This is not good news for the Paul campaign as bad weather would help those candidates with hard core supporters. Good weather will result in a stronger turnout and that should help with candidates like Romeny who could attract the undecideds.
Of course TMV would not be TMV if there were not people to disagree with me, so feel free to chime in with your own predicitions.