For holders of a Delta American Express card, Gary Steiger of Free Frequent Flyer Miles posts a useful tidbit:

Current holders of either a personal or a business Delta American Express credit card that is not translucent can get 1000 miles through December 31, 2003, for switching to a translucent card. Call (800) 297-6200, press 3, then press 1. A live person will handle the transaction. This phone number is for business cards, but it also works for personal cards. Note that the new card will have a different account number on it. But the customer rep I spoke with said that bills paid by and to the old account will be transferred to the new one automatically. I would change all of these billings anyway, but you probably have some time to do so.