Disney has not announced discounts for December 2010 dates. If 2010 is similar to last year, discounts will be announced late July. Again, IF similar to last year there will be a room-only discount and/or free dining.
We stayed at a Ft. Wilderness cabin last December. I called on the first day the discounts were available to the general public (they'd been announced for Disney Visa customers a couple days prior) and was able to book the free dining package for our dates in early December. This was a particularly good deal for us because we had 4 adults and 2 kids eating for free on our reservation. If we'd paid for the dining plan it would have cost approx. $200 per day! When I called the room-only discount was not available for our dates.
We absolutely loved staying at Ft. Wilderness during the holidays. The campers go all-out decorating and the Fort becomes an attraction in itself. The peace and quiet of Ft. Wilderness is so refreshing after a day in the parks and our kids loved having space to run around outside. We requested a cabin in a loop close to the quiet pool so we were near the pool, laundry and extra restrooms. We rented a golf cart, which was expensive but so much fun and super convenient. If you don't want the added expense, the buses run frequently inside the resort.
As far as dining, Trails End (buffet) is the only restaurant in Ft. Wilderness. There is a small ferry boat that goes between Ft. Wilderness, the Contemporary and Wilderness Lodge. We enjoyed taking the boat to the Contemporary and eating at their Counter Service restaurant and Chef Mickey's. If you'd like to schedule table service meals in the park, check out the park hours and nightime entertainment schedules to figure out which parks you'll be in on which days and make ADRs for the restaurants you are interested in NOW. If free dining is released for those dates the restaurant availablility will be scarce!
Feel free to post any other questions you have and check out the camping board for more info on Ft. Wilderness. There are also several threads on the Resorts board with people waiting for December discounts. If you keep checking on here you won't miss the discount news if/when it is released.