Preheat oven to 325Â°F.
Remove and discard casing from ham.
Using a sharp pointed knife, score top of ham in a diamond pattern (cutlong diagonal slashes, about 1 1/2 inches apart, in 1 direction, then cut across these slashes in other direction); stud the intersection of each "diamond" with a clove.
Transfer ham to a 1-quart casserole and arrange pineapple slices on top of meat; pour ginger ale over ham and sprinkle each pineapple slice with dash cinnamon.
Bake until heated through, 25 to 30 minutes.
Serve 4 ounces sliced ham and 1/2 pineapple slice per portion.