I have only watched the first hour of this, but I already highly recommend that you watch it. It will be replayed several times on HBO over the next month, so please try to catch it. If you don't have HBO, find someone that does! Here's the info from the HBO website:
HBO: When the Levees Broke: A Requiem in Four Acts One year after Hurricane Katrina decimated New Orleans, director Spike Lee presents a four-hour, four-part chronicle recounting, through words and images, one of our country's most profound natural disasters. When the Levees Broke Acts 1-4 air on the anniversary of Hurricane Katrina: Tuesday, August 29 at 8pm.