I'm with Paul. The mistake people make at Boston is they go out too hard, regardless of the weather, right? This forces us (hopefully) to dial it back and not do anything stupid in the first half of the race.
Good advice on not dousing your face with Gatorade!
Fast times have been run in these conditions (Beijing 2008 comes to mind... and heck, its the 30th anniversary of the Duel in the Sun!). And it shouldn't be humid, so at least we have that going for us.
I thought the same thing about Beijing. But this was the best marathon runner ever you're talking about. The more elite the athlete, the more they can overcome adverse conditions (ie - heat, wind, hills, etc). Most people still wilt in the heat, barring Wanjiru, Salazar, and Beardsley and a few others. Still, lack of humidity will help.