I found the interview where she talked a lot about the song. It was an interview she gave with LiveDaily on May 3, 2007, while promoting Crystal Visions. Here's the excerpt:
Have you started writing material for a new album?
I have. It's not like I'm writing new material for a new album; I'm just writing because I always write. I've written a song about New Orleans that I really love that's kind of about [Hurricane] Katrina. I was going to put it on this record as just an extra, added thing, then I pulled it because I'm not ready to release this song yet. I don't have the time to go out and find the right producer for this song. I'd like to have it be a real New Orleans flair. I live in Los Angeles. I don't really know anybody with a New Orleans flair here. I made a really, really good demo of it and it's sitting in the demo trunk waiting for when I have some time to do it. When this tour's over at the end of the summer, that's probably one of the first things I'll do is find somebody. I want to get this song recorded. I don't think it will matter if it'll take another two years to come out, because New Orleans is not getting better overnight. I think it's going to be relevant for the next 10 years, [so I'll release it] whenever I get it done to the point of where I think it's really ready to help that city. That's what I want to do with it. I want to let it go somehow someway to help them. Whether it's just giving the song royalties over to the city of New Orleans or what--but something. I'll figure out something. I didn't want to take a chance of it not being done, as good as it is. I think it's one of the best songs I've written in a long time.
http://www.livedaily.com/interviews/...2039.html?t=98