I'm pretty sure they do take credit (amex, discover, visa, mastercard, etc), but I can't remember. I have used my room key at most of them in the past.
I'm pretty sure they do... I used my MasterCard and Diner's Club card at a couple of counter service places when I was low on cash. I think the only places you can't use your charge cards are the little vendor carts in the park that sell soft drinks and ice cream... they only take cash.