It certainly doesn't hurt his chances. He nearly made a misstep beforehand though when he said he thought he'd win Iowa. It was unnecessary to make such a statement in a place he didn't even need to win. It was a very close call indeed.
I read on a political blog that exceeding expectation is really what provides a boost during the primaries. By that measure Santorum will likely see a bump in his popularity in New Hampshire and beyond. Ron Paul will get a boost too. In many ways Romney benefited from a split field, with various conservative options to choose from. As they drop out, there's always a chance that another candidate will pick up more and more of the vote.
Realistcially though I'm say that Romney is firm favorite. All of his opponents are viewed to a pretty conservative so there is no-one to his left to split his vote, and no one candidate to his right that voters feel confident to rally around.