Some people are quite sure they know what God wants. Just ask 'em. ;-) Some have radio shows about it and make big bucks. Sounds to me like Nagin got a little carried away with his oratory, but it's not unusual for people to think that a disaster is God's punishment on a wicked humanity.

In the case of our society's industrial pollution causing global warming and quite possibly contributing to more extreme weather, you could sort of see a kind of retribution in what happened this past year...by Mother Nature or by "God" (however you define what's out there). After all, what is Mother Nature but the most easily observable face of God? (assuming you can relate to such a concept in the first place)