Mark Blumenthal downplays the likelihood of polling tempest:
…we can probably dispense with the "Perfect Storm" analogy. In the movie of the same name, three different weather-related phenomena combined to produce a storm of exceptional severity. In this case, as Democratic strategist Joe Trippi pointed out in September, the potential polling foibles may work in opposite directions and "cancel each other out." A return of the Bradley-Wilder effect would work to McCain’s benefit, while an underrepresentation of younger, African American or "cell-phone-only" voters will likely benefit Obama.
The Dish 