UPDATE
Now with only 4 weeks left, Obama's probability has dipped to 78.4%, from last Monday's 85.1%. The electoral forecast now sits at 308 to 230, down from 320 to 218.
Interestingly, last Thursday evening (24 hours after the first debate), Obama's probability had risen to over 86%, but sunk 8 points over the weekend. Apparently Romney's spin on the unemployment numbers and his 47% apology carried more weight than the debate.
http://fivethirtyeight.blogs.nytimes.com/