The biggest question in my mind about the low turnout at airports is what percentage of people decided not to fly because they didn't want to subject themselves to scans and Freedom Frisks, and what percentage decided not to fly because they didn't want to deal with the huge delays that NOOD intended to cause.

Barring somebody actually taking surveys on that question, the way to tell will be to see whether people continue to not fly in the coming weeks, or if they only avoid airports today -- remember, the scanners will continue to be there, but NOOD was a one-day affair.