SSTs recover fairly quickly after a storm's passage, even a major hurricane. That's not true, however, for the sub-surface waters. Hurricanes can affect waters 70-100m deep through mixing processes, with stronger storms able to affect a greater depth. These waters also take longer to warm back up than do the SSTs, whether through currents, mixing, or old-fashioned heating from above. The waters in Katrina's wake are nearly back to normal at the surface -- still below what they were earlier this season, though -- but I would imagine that the below-surface waters are not. This would serve as a cap to the intensity for anything passing through there, whether moving fast or moving slow, though it is likely the waters could still support a category 2 or so hurricane. Not saying that there will be one there, but I think that's about where the true maximum intensity for that region is (under ideal conditions) right now. It'd probably take the rest of the season for the entire depth to warm back up and, with cold fronts starting to make their way closer to the coast, there would be little time for anything substantial to tap those waters. Of course, that brings up the question of a storm forming off of the tail end of a cold front there later in the season...but we'll leave that for the appropriate time.