I honestly don't know. It's less than 4 weeks away, Akin has no money, and McCaskill's got a ton of PAC support. She keeps throwing snippits of his own words in his face and I don't know how effective that is. This week's polls should prove interesting.
In the end, if Akin wins then I think it'll be for the same reason Romney wins - people vote against the opponent rather than for the candidate.
He'll win.