"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
iPhone 4S Includes Significant Antenna Upgrades
"With the iPhone 4," Webb explained, around the steel band "we had one cell antenna at the bottom. On the top, we had another antenna for GPS and Wi-Fi." This turned into Antennagate.
With the Verizon/CDMA iPhone, Webb believes Apple's designers "moved the GPS and Wi-Fi antennas beneath the back glass and turned the top antenna into a second antenna for the cell phone." This brought spatial diversity to the iPhone. This design helps solve the Antennagate problem, because the phone can switch between the antennas depending on signal conditions.
"If you cover up an antenna, you're probably not covering up both antennas," Webb explains. "Spatial diversity on the receiving side is required for use with the Verizon network."
The Verizon iPhone had 'receive diversity' -- it used two antennas for receiving data, but may have only transmitted on the bottom antenna. With the iPhone 4S, Apple claims to have both 'send and receive diversity' for GSM and CDMA. They're using this diversity as the solution to the antenna problem.
"The iPhone 4S may indeed be the first phone to have diversity on both the send and receive sides, and that is a decently big deal. They still have the antenna around the rim, though, so it's evolutionary, not revolutionary."
Image via This Is My Next