For returning B/G's considering obtaining an anniversary cake, here are the guidelines set by Disney as of last fall.
Anniversary cakes for the Grand restaurants and room service are made at the Grand Bakery. The Grand bakery is responsible for 95 percent of the wedding cakes on property. Due to the increase in business, the Grand bakery has delegated the anniversary cakes not served at the Grand to the other bakeries across property. Those bakeries are supplied with the same recipe's as the Grand, so your cake will taste the same as your original. The only exception is the Magic Kingdom, as they employ an outside company. If you truly want a cake from the Grand bakery, then I suggest that you try and contact you EM from your wedding, and see what they can do.
The Grand bakery no longer provides cakes for pickup, as it was unfair to ask the guest to find transportation across WDW to pick up their order when the other resort bakeries could provide the cakes. In addition, most guests had difficulties transporting their own cakes, resulting in damaged cakes and dissappointed guests.