Here's my take on heavy turnout....
Imagine you're a 20 year old college student who generally doesn't care about politics but went to a rally to see P.Diddy and he told you to vote. You show up on election day and the lines are really long. The wait could be 3-4 hours, maybe more. You have a big paper to write and a test to study for. Do you stay in line waiting to vote or do you give up??
I think a lot of the apathetic sKerry supporters would be more inclined to walk away than to stand in line for a long time. Especially if it's cold outside or the weather is bad.
Well that is a good take, but also remember that Republicans have been registering new voters too, and that in 2000 something like 8,000,000 Christians stayed home because they felt GWB wasn't Christian enough, not the case this time, they are coming out in drives and are motivated.