Actually, no it does not do any damage to the joints. It may cause some temporary pain to avid crackers, but that is relieved by taking a crack break. Other than that it is just annoying and does not cause any future arthritis.
My sister always cracked her knuckles when she was younger. Now all her kids do it. She says it's a great stress reliever. And , no, she has not developed arthritis; and her knuckles are not huge either!