We were there last year for free dining the last week of August. The parks were quite empty. We left for Fla. on the day that Katrina was making ground in Florida (worried we wouldn't be able to land - but we were fine, as we all know).
I do believe that Katrina impacted the crowds at Disney. Here's some examples: We were staying at the Beach Club. On the morning we went to AK, we were the only people on the bus (we shared with Yacht Club). I could not believe how little the crowd was waiting for AK to open. One afternoon, we left for MK (around 2:30), we were the only family on that bus as well. There really were no lines anywhere - Soarin' had the longest lines at Epcot. I only saw 60 minutes on a couple of rides (SM is the one I recollect). Friends we were with go to WDW at the time every year and say it really is not crowded.
We are heading back this year. I'm curious to see if it is any different.
Anna