The last day to book was yesterday (8/28). From what I've read, guests saw info on flyers/letters in rooms, on Resort TV and on resort restaurant receipts. It had to be booked on or before check-out, and on or before 8/28. Guests had to call a certain extension and book it with a $200 deposit. Not all guests received/saw the offer, but many found out about it here on the DIS and on Mousesavers.com.