A newly-leaked rear panel -- said to be for the iPhone 5S -- suggests some changes to the iPhone's home button. The panel shows rearranged screw placements versus the ones for the iPhone 5; likewise, the part is paired with a metal spacer cushion using a different, asymmetric design. Holes and screw placements around the camera area are also changed, but the home button design
may be the most significant.
Despite one part leak
possibly pointing to the contrary, the 5S is commonly expected to adopt a fingerprint sensor
built into the Home button. Apple would presumably need to alter the button to fit extra circuitry and/or cable connections. No buttons with the technology have so far been leaked, however.
A fingerprint sensor could have several purposes in a new iPhone. While it might just be used to quickly unlock a device, it could also allow for multiple user accounts. It might also be tied into a rumored NFC-based payment system, lately hinted at by plans for Isis support on the iPhone