I've made "Steakhouse mashed potatoes" with baked potatoes. Instead of milk or cream I used sour cream, butter, and sliced green onions or chives. I fluffed the inner potato, leaving the potato skin for later use, and mixed in the other ingredients. I served it with steaks, I don't know how well it would be paired with turkey.

For mashed potatoes, not really, but there are plenty of other things you can do with baked. For good mashed potatoes (as in really creamy and smooth) it's best to boil them and then put them through a potato ricer.