Whenever there is a major world event, a significant portion of the population goes to fill up their gas tanks. This is human nature and, frankly, I do it, too.
Anyone knows what happens if most of the USA goes to the pumps on one day and tanks up?
Shortages. Now, is this a real shortage? No. But suddenly all the sheep realize that the tanks at the gas station are not bottomless, and that there is a real potential for a short-term shortfall. Suddenly, everyone is buying gas cans and hoarding what gas is left.
Couple this with the very real mid-term shortfall that Katrina's damage will cause, and you have a serious panic situation in regards to gasoline. This is why gas stations are driving their prices up now, because price moderates demand. If you go to the gas station, intent on topping off your car and filling up a few five-gallon cans and see prices of $3.00/gallon, you will probably go "Uhm...maybe not", unless the sitaution is really bleak. The price hike is a way of keeping the supplies we have availiable to those who really need it (read: those who will pay) and generally smoothing over the whole crisis.
I don't like the price hikes- my truck has a 25 gallon tank and I get 15 mpg. But I recognize them as a necessity.
Mike