We stayed there in September 2007 - during free dining - and were still able to walk in several times (at least 3 or 4 times). Even once for dinner with 7 people. Off peak lunch was usually deserted. I think we waited for about 35 minutes for dinner with the party of 7.
We just got back y'day and managed a walk-up Friday night. We had to wait for about 30 minutes but they did get us in. I was told at alot of the restaurants that they didn't have any reservations available but that they saved some seats aside for walk-ups.
I would not count out the possibility of walking in at dinner without an ADR. Last August during free dining my family and I were visiting the Polynesian and Kona Cafe was busy and this was during dinner hours. Anyway just for fun we asked could we be seated without an ADR and the Cast Member said yes, however it would be at least 60 minutes or more. So even though it would have been a long wait we could have got a table, so anything is possible.