Update 6:15pm: Consider this poll with Nate Silver's qualms in mind.
It's Obama 49-42 over McCain according to a new Columbus Dispatch poll of 2262 likely Ohio voters with just a two-point margin of error. (The poll covers 9/24-10/2 and thus doesn't reflect the Biden-Palin debate.)
Falling far behind in Ohio is a nightmare scenario for McCain; he almost surely can't win without it.
And remember, absentee early voting has already started there.