I think if you are going to take an environmental stance all the city dwelling commuters (the ones who drive an hour+ each day) are the real offenders, Trucks or not.
I'm considering buying a Truck, but I work from home and drive only a few thousand miles each year or less.
Though the real answer is a truck for times when you need a truck, and bus/bike for everything else. Too bad transit in the US is in general horrible.