My math might be off but.....1 Gallon equals approximately 3.785 liters. Therefore, if gas is costing us (Americans) approximately $3.50+ per gallon, that's $0.925/Liter, or $1.20 Australian once you convert it for Chesty Bonds.
Its not cheap, but its a far cry from the amount the english or any other european country pay.
The real question should be why the prices shot up so fast. There's typically a week+ lag time in the price of crude and what you see at the pump, and yet just hours after Katrina hit, the prices were shooting up. The gas companies will claim they were worried about supply shortages, but I suspect they were hoping to quickly cash in on the economic confusion that immediately followed Katrina.
So long as there are fewer Suburbans, Hummers, and Expeditions on the road, I'm happy.