Dale gave a great detailed answer.
Or as another short answer, the buyer has until 12/29/08 to decide if they want to move forward with the purchase or not. If they do, the status will change to pending or if they decide to back out, then the house will be active for anyone to submit an offer to the seller.
Ask your agent to check on the status tomorrow. It should be updated but sometimes listing agents take a couple days to update it.