Listed on their website but no details yet other than these:
Start planning your fall vacation now and treat yourself and someone special to all the charm our resorts have to offer. Enjoy a free night (based upon a minimum length of stay), a 1-category room upgrade and full American breakfast for 2 daily when you book the Three for Free package. Stay between September 1 and December 19, 2008. When you book and pay with any American Express(R) Card, you also receive a luxurious welcome amenity and late checkout. Use the extra time to take advantage of all the excitement our resort destinations have to offer.