According to this AP story, Katrina has been posthumously downgraded to a Cat 3 landfall, rather than Cat 4:
The revision of Katrina’s strength came after forecasters studied data from devices that were dropped into the storm from aircraft, the report said. The change also came from reviewing readings from a device that measures speed by examining how sea foam is blown.
And the levees were supposed to have been engineered to withstand a Cat 3 storm… although, other published articles have pointed out that there are several reasons why the levees may not have been up to spec.
I’m sure that the folks suing the Army Corps of Engineers and the Levee Districts will find this news helpful.