After last night's debate, Obama's stock is trading this morning above $6.40, indicating a 64% probability of victory (see here). At least according to the Intrade prediction market's more or less instant analysis, Obama won the second presidential debate. (CNN's post-debate poll of debate watchers reached the same conclusion, see here). Of course, polls and predictions are one thing; elections are another. Still three weeks of mud slinging to get through before election day.
UPDATE: Just for a change, I decided to check how actual bettors in the UK are viewing the US presidential election campaign. At Ladbrokes.com (here), Obama's odds of reelection are 4/11, while Romney's odds are 2/1. In other words, if Obama wins an 11 pound wager would earn 4 pounds; if Romney wins, a one pound bet would earn 2 pounds. Obama is a clear favorite at this point.