Although this isn't a 100% guarantee that Cataclysm will be released January 3 or 4th there is good evidence that it might be released that time. Amazon released a delivery date this morning to all it's users who preordered Cataclysm. Below is the picture of the date.
The stores do not have a fixed releases date because nothing has been confirmed by Blizzard, heck my preorder states 2nd November.
