The refining capacity argument is a little misleading. The lack of refining capacity in the US is not really a big bottleneck at the pump. We can and do import vast quantities of refined petroleum products from overseas, where there is no shortage of refining capacity.
Basically, we've outsourced our refining operations to foreign countries, and thus, given them the opportunity to employ their people in these very good jobs, at our expense. But it doesn't have that big of an impact on the price at the pump.
Of course, it does take time to transport more refined products to the US if there is a disruption, as in the case of Katrina, but other than that, and the cost of transportation itself, the lack of refining capacity is not the big buggaboo it's made out to be, at least in terms of the cost of gas.
But this cannot be a noticable impact as we were transporting most of the crude oil to refine in the first place.