According to CNN, NOLA Mayor Ray Nagin is strongly encouraging residents to evacuate, and it appears a mandatory evacuation will go into effect for the city later this afternoon. The lines at the Union Bus/Rail Terminal are being reported to stretch for miles. They also reported Louis Armstrong International Airport will be closing at 6 p.m. tonight.
Mandatory evacuations are also underway in all the southern coastal parishes of LA attm.
Even if Gustav does wind down to Cat 3 status before it makes landfall, it's still going to have one hell of a storm surge built up with it, and with the complete destruction of many of the protective barrier islands in the delta by Katrina three years ago, the storm surge is going to likely be significantly more destructive than Katrina's. If Gustav's eye tracks just southwest of the city as currently predicted, the resulting storm surge flooding is going to make Katrina completely pale in comparison and you can kiss New Orleans goodbye...
EDIT - I was just viewing the visible satellite loop, and Gustav has made a distinct wobble to the right in the last few frames of the loop. This wobble is also visible on Cuban radar. This is bad. Very, VERY bad...