EIA on Katrina impact:

http://tonto.eia.doe.gov/oog/special/eia1_katrina.html

snip:

As of August 19 (the most recent data available), U.S. commercial crude oil inventories were well above the average range for this time of year. However, gasoline inventories were at the lower end of the average range, and with demand growing at a 1.6 percent rate over the most recent 4-week period, in terms of the amount of days gasoline inventories would supply, they are very low. Distillate inventories remain above the average range for this time of year. Inventory data as of August 26 will be available at 10:30 am ET on Wednesday, August 31.
I'm guessing that this is why the NYMEX wholesale price for gasoline rose over 41 cents/gallon today.

My hunch is that heating oil will be very expensive this winter (above $3/gallon), but not in short enough supply that people will have to do without.  Gasoline could rise a lot more in price (above $4?), and might even see some regional, short-term supply problems.

Look out the nearest window, people.  This is what interesting times look like.