Hi, I'm a FEMA point of contact on this.

Shape files can be found here:

http://www.gismaps.fema.gov/2005pages/rsdrkatrina.shtm

The older ones likely reflect how much assessment has been done rather than how much flooding occurred at that point in time.

We should have this page cleaned up with updates in the next few days. We will continue to provide Google with updates.

Regards,
-Scott