The New Orleans fiasco should make it very clear to everyone that the Department of Homeland Security is a sham.
The logistical challenges are exactly what DHS is supposed to be expert about, but the evidence so far is that their expertise and preparedness are literally zero. (Presumably the fiasco in Baghdad has similar roots-- giving another billion to Halliburton would not be an efficient way to fix New Orleans.)
In the aftermath of this, every American needs to confront their local experts to make sure that their community doesn't become the next New Orleans... so we all need to understand the challenges, since DHS doesn't.
Terrorist attacks, weather catastrophes, chemical spills, epidemics-- the challenges are basically the same everywhere.
One of the most useful insights I've seen was on the Huffington Post, pointing out how everything else depends on the communication systems working, especially the radios for police and other emergency responders. You have to think thru where these systems are vulnerable, and what you do if they fail.
Telecom is cheap these days, and there's no reason that a full substitute citywide wireless system couldn't be deployed within hours, if anyone had made the investment beforehand. A stockpile of devices that gets upgraded each year, and exhaustive scenario-testing of how best to put them into use.
One of the unexpected things about New Orleans is that the communication is so devastated that rumors are out of control-- nobody seems to know where the need is greatest. There should be a communication center dominating the cable news coverage, collating reports and squashing false rumors, updating a map that everyone can refer to.
Another obvious problem is local transportation-- New Orleans seems to be relying on helicopters that can't begin to deal with all the stranded people. Why wasn't there an armada standing by, of canoes or rowboats or whatever, that could be going door to door in the flooded areas? Why weren't as many as possible of the blocked navigation routes cleared immediately? (Hindsight is easy, but the point is to use the lessons, to think thru all possible next crises.)
Emergency housing is a vast problem-- we should be ready to turn any empty field into housing for 10,000 refugees in 24 hours. The military knows how-- why isn't this a no-brainer for the DHS?
When the levees survived the first 12 hours, the first priority should have been to monitor their continued integrity, with detailed plans for stopgap repairs, but this seems to have been completely overlooked. Every sort of catastrophe will have comparable critical vulnerabilities, and we have to think them thru in advance.
I suspect the skill that this sort of foresight requires is rare and unfamiliar to most people, and especially to bureaucrats. It seems to me much more like the novelist's skill, and I think composing realistic short stories about possible catastrophes is a valuable exercise that anyone can undertake. (I wrote one in 1996 about an atomic blast under the Sears Tower, and the big lesson that jumped out was that we need a strategy to smother the fires in the aftermath, so the radioactivity doesn't spread. But I doubt anyone in DHS is thinking about this.)