Yep, right about that, Obama just got a whole lot harder to defeat in 2012! Obama is the POTUS at the time when Bin Laden was killed, he gets the political credit(better or for worse).
Don’t think it is a factor. maybe a 3 on a scale of ten. Certainly doesn’t hurt, but if the economy is still in the toilet, there will be a new President in 2013.
As a reality point, this is a great event, but really not overly significant. It is unlikely the guy had much at all to do with AQ operations. Obama hasn’t mentioned OBL anytime in my memory since the campaign. It is a positive event, but doesn’t get anyone a job or fill their gas tank or grocery cart.