Funny, I've been in this exact situation, right here at home, when the Delaware River floods happened, both in April 2004 and September 2005.
First of all, shelters suck. There's no nice way to put it, they are not a fun place to be, ever.
One of the most important things to do is to triage people's attitude. There's several classes:
1. Whiners. (It's so cold, it smells, I'm hungry, when can we go home, where's my dog? my cell phone does not work, isnt' there anything else on TV?)
2. Helpers. (What can I do? What do you need? Where should I bring this box?)
3. Helpees. (I actually need help here, because I can't walk/breathe/stand whatever).
4. Self-Appointed Experts, Slime-Molds and Scuzz-Balls (opportunistic creeps who generally make a bad situation worse)
In proportions, you have 70% helpers and a random distribution of the rest. That's good. Unfortunately, the rest can become a bit annoying to those people charged with operating the shelter.
For the most part, if you have a decent action plan - or for that matter ANY action plan - and you can devise a way to maximize your "Helpers" it seems to go well. For example, story time for the kids is a great use of helpers.
One other thing I learned is the a lack of sleep leads to very, very hot tempers (in me and in others) and a break of the "routine" is exceedingly distressful to people. For example, just closing a road in our area generated altercations that were quite dramatic.
Boredom and a lack of information is a huge factor.
One thing that really made things go well was an internet connection and a large video projector that allowed people to see the weather report, the river crest forecast and general news and information as we got it. I was able to build a simple web page with all the basic data on it, and we set that up at the fire house.
As far as food and sanitation, that was a job for the "Helpers". We had to make some meals for the firehouse and people of the community, we just told people we need food, and the food came. We told people we need fuels (gas and diesel) and the fuel came. I think that was the biggest lesson for me. Give people something meaningful to do, and they will be aligned with you to deal with the situation. It's those with nothing to do that cause all the problems.
Oh, and, after the April floods, when the river came up again in September....yes, I did decide to carry a gun. The flooding in September was major (3rd worst ever recorded), and the scope was greater, the population affected larger and the level of anger that ended up directed at anyone at all higher. I never needed to show or use it, but I can assure you that personal security was, and is an issue in these situations.
While the situation in NOLA was, perhaps, the most extreme example of a shelter situation gone bad, to be honest, I can see the ingredients of it all right here in an affluent community. It might not go quite as far, and it might not happen quite as quick, but the altercations that did happen were frightening in their speed and ferocity.
One thing I'd LOVE to see as a "Standard Issue" in shelters is this:
http://www.mobileinternet.bz/index.htmor something similar.