"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
iPhone 4S Sales Now Reservation-Only at Apple Retail Stores in U.S. and Canada
Apple has updated its "how to buy" page for the iPhone 4S to note that Apple retail stores in the United States and Canada are now selling the device on a reservation-only basis. Customers will need to visit Apple's site after 9:00 PM each evening to reserve a phone for the following day.
iPhone 4S is available in store by reservation only. Reserve yours after 9:00 p.m. tonight for pickup tomorrow. When you come in, you’ll choose a carrier and plan, and we’ll get your iPhone up and running before you leave the store.MacRumors spoke to a representative at one Apple retail store who noted that that location continues to sell the iPhone 4S to walk-in customers but that supplies are "evaporating". But as supplies tighten Apple seems to be pushing customers toward the reservation channel in order to minimize lines and disappointed customers.
It seems unlikely that Apple retail stores would refuse to sell unreserved iPhone 4S stocks to walk-in customers, so the company may simply be taking reservations and then distributing any remaining stock each day on a walk-in basis.
Apple is placing some restrictions on iPhone 4S walk-in sales in other countries as well, noting that it will take reservations for both on-contract and SIM-free iPhone 4S models after 9:00 PM, but only on-contract phones will be offered on a walk-in basis in those countries. Limiting walk-in sales of SIM-free handsets is likely designed to discourage mass sales into the grey market, such as in China where the devices are selling for as much as $2000.