This is the final snapshot from Pollster (which isn't a poll itself, but a conglomeration of all polls).
As you can see, Gingrich's surge is all but over, and Paul's is on the decline. Santorum's surge is well-timed. He could even win. The top tier is Romney, Paul and Santorum.
Don't be surprised if Santorum wins. This is an evangelically conservative state — in 2008, their man was Mike Huckabee (and look what happened to him). People might be concerned about Santorum's positions (most recently, he's saying that states should have the power to outlaw birth control), and those positions might fly in Iowa. But Iowa is hardly mainstream America.
What else can be said? Things looks bad for Perry and Bachmann. Iowa may be the end of the road for them. Huntsman is of course doing badly in Iowa — he barely campaigned there. So it won't be "bad" if he makes a bad showing.
Also, Romney is sitting pretty. Even if he comes in second, or even a tight third, he's going to do well in New Hampshire — a landslide according to the latest polls. Huntsman is polling third in NH, which means he'll still have life — barely — especially if other candidates drop out.
Gingrich can last a while, even with mediocre showings in Iowa in New Hampshire. He doesn't have a lot of money, but he doesn't spend a lot of money either. South Carolina is going to be his mother's milk.
But Iowa, I believe will be the beginning of the end, if not the actual end for Bachmann and Perry. That will be its significance — not, who won.
By the way, this might be a good time to remind ourselves on the f'ed up way that Iowa caucuses operate.