Apocalypse in slow motion.
For a while, it looked like New Orleans would escape the worst-case scenario. God still forbid, but now it looks like Prof. van Heerden's nightmare may be coming true.
The Governor of Louisiana has just ordered the total evacuation of New Orleans. The levee breaks have flooded 80% of the city. As this helpful map and diagram note, the situation is dire with water pouring in from the shattered levees along Lake Ponchartrain. The Tulane University Hospital is particularly vulnerable. It's going to take a Dunkirk effort to get them all out, but it's possible.
Remember also in your prayers the people of Mississippi, who took the sledgehammer brunt of the storm. At last word, hundreds may have died in the Gulfport area alone, where the storm surge reached 30 feet. The authorities simply do not have any reliable figures yet.
Again, the American Red Cross is doing yeoman's work. They are worth your hard-earned treasure. An awful lot of lives are going to have to be rebuilt, and it starts with something as simple as a hot meal and a safe place to stay.