I dont think the price of gas hurts fullsize trucks all the much because most people who buy those vehicles buy them because they need them.
Believe me, Id love to be able to move to a Focus or Fusion, but for me personally its just not practical. I haul firewood with my truck in the summer (I heat my house with a Vermont Castings wood stove and it saves me a lot of money on my heating bills) and I haul my snowmobile in the winter. Plus, there are various other times when I just wouldnt want to be without a truck. For me, a car really isnt even practical, no matter how expensive gas is.
The price of gas is not just due to the war in Iraq. China is using more and more oil, and that plays a role as well.