The link above to Wikipedia has a pretty good round-up of "what went wrong" in its article on the political impact of Hurricane Katrina. Last night I ran into the stunning fact that the National Guard prevented people holed up at the Convention Center from walking across the bridge to escape New Orleans. I imagine they were concerned about a flood of people going into the next town, or whatever. It's bad enough that there were these ridiculous delays in getting help, but to even prevent people from seeking food and water on their own is just unimaginable cruelty. It's like locking someone in a prison cell without food and water.
During the disaster, I've been watching CNN, but I found some dramatic footage from Fox with Geraldo Rivera and Shepard Smith getting very emotional and pleading for these people to be let out of the Convention Center, to walk across that bridge to where food and water was. This was Friday, when the trucks and buses started rolling -- but the people at the Convention Center were still without food and water when this was shot, and there was no information about when it would arrive. Take a look; you won't soon forget it.
You know what's really amazing? That there wasn't a riot. If I'd been without food or water for six days, with old people and babies dying around me, and soldiers told me I couldn't go to where food and water could be found, I'd just say "Shoot me now. Better to die fast than slow." By not letting people through, they were killing them just as sure as putting a bullet in them anyhow. Why didn't the guys who set up this checkpoint have supplies to give these people? It just boggles the mind.