I just saw on a facebook post from couponing to disney:
"I have very exciting news. Disney World will also send you an autographed picture when you write a letter to the following address:
Walt Disney World Communications
P.O. Box 10040
Lake Buena Vista, FL 32830-0040
We wrote a letter to Cinderella and received an autographed 8×10 colored picture within 2 weeks."