I got different rates for January 2013 depending on the day/resort. I got 10% off the Thursday before MLK in a Little Mermaid room at AoA. No discount for MLK weekend nights. 10% off a Nemo suite the Monday to Wednesday nights following MLK weekend and 15% off Wilderness Lodge Thursday 1/24 to Sunday 1/27.
When I was deciding what resort to stay at, I also priced out Grand Floridian regular and club levels, Polynesian, and Contemporary and they all were 15% off from Thursday 1/24 to Sunday 1/27 too.
I'm thinking the discount probably changes depending on the season and resort. I was a bit disappointed with no discount over MLK weekend since I had read that only Christmas time had blackout dates.