I can't overemphasize all the small delights in the piece. WalMart devotes just a few people to handle disaster planning full time with fifty more on-call in case of an actual event. I doubt any state has that few people available and can match WalMart's effectiveness (much of the article compares government's crappy response to WalMart's successful one).
WalMart has a strict "no gouging" policy on pricing - prices are frozen the day before an expected disaster. This is a PR move and not a social good. I'd rather see the price of scarce goods double in disaster areas. If you buy flashlights at the normal price you might buy one each for the kids and leave none for the next guy in line. If they are expensive you might just buy one for the family. On the other hand WalMart is so good at supply they almost never run out of anything.
Unlike FEMA WalMart knows how to delegate, here's a snippet from the CEO to store managers before Katrina
This company will respond to the level of this disaster. A lot of you are going to have to make decisions above your level. Make the best decision that you can with the information that’s available to you at the time, and, above all, do the right thing.Store managers responded by doing a variety of things depending on their own circumstances. At relatively undamaged stores they took IOUs from emergency responders. Damaged stores moved as much stuff into the parking lot as possible and handed it out gratis. A few stores that were overrun with looters (and the looters included police officers) were just abandoned.
WalMart has dedicated emergency supply warehouses scattered around the country. These are stocked with region specific disaster supplies. During normal times they rotate the stock into the regular supply chain but when disaster strikes they empty them into the affected region.
Like I said, there are many small delights to be found in the article. Johnathan Pierce at Samizdata uses as a hook to discuss corporate responsibility (and probably not in the way you are thinking of).