Seems to me that it is being used to dispatch the National Guard and/or the State Police that arrived yesterday in the city that FEMA forgot. I listened off and on today and my guess, from the type of language used, is that the State Police are the ones being dispatched. The National Guard is a little more formal and technical with their radio language.
At the same time, I noticed no increase of activity on the National Guard talkgroups since thier deployment to New Orleans. The little that I did hear didn't seem to have anything with patrolling the city. It was pretty interesting though to hear them ramping up to head to NOLA on Tuesday.
I guess they are dispatching on the State Police coordinate talkgroup since it may quite possibly be the only way they can accomplish interoperability between all those involved. Then again, it may be for a totally different reason. Either way, it's been fun listening.