MSN Money
You can have all the oil in the world and still run short of gasoline, however, if major refineries are out of action. Refineries are large, smelly, unattractive plants that “crack” crude oil’s hydrocarbons into the stuff that makes modern life go, such as heating oil, kerosene, jet fuel, the feedstock for plastics, diesel and automotive gasoline. Few U.S. states have ever wanted these noxious beasts on their coastlines, so the ones built in loosely regulated Louisiana half a century ago make something like half of all the refined crude oil products in the country. When Katrina blasted through, her high winds and storm surge knocked these plants for a loop, and the partial shutdown caused 10% of the nation’s entire supply of gasoline to vanish in a weekend.
Read the whole thing, it's a good article that dispels a lot of the myth behind most pricing, including labor.
Update by Rob:
There's a strong case to be made for taxes being culprit in higher-than-necessary gas prices:
Today, the combined burden of federal, state and local gas taxes costs American drivers an average of 45.9 cents on every gallon purchased. As Figure 2 illustrates, in some states the combined taxes exceed 60 cents for every gallon purchased. In these times of concern over high gas prices, American consumers should remember that gasoline taxes have a significant impact on the amount they spend at the pump.
California is one of those $0.60/gallon states. According to the last census there were 33,871,648 people living in California, not counting the millions of illegal immigrants. Clearly the municipal, state and federal government is raking it in when every gallon of gas bought by those millions of drivers puts $0.60 in their pockets. That's $12 on an average 20 gallon fill-up.
Now tell me there aren't some things in collective government budgets that couldn't be cut to make way for some gas price relief for American citizens.