Watch out. The first round of exit polls will not catch people who have jobs and are voting after work. Youths and minorities will vote earlier in the day, so of course they will constitute an outsize percentage of voters when the 5:00 PM round of exit polls are released.
Remember in the Wisconsin recall, the 5:00 round of exit polls had the race tied. The final round of exit polls, which are released after polls are closed, showed a Walker victory.
Look for Axelrod to start proclaiming victory based on the first round of (minority-skewed) exit polls.
Rumor on twitter is that Obama knows they are losing Ohio based on turnout so far which is why they dispatched Biden to Ohio today...