"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Photos of Alleged Packaging for Official Apple iPhone 5S Leather Case Surface
This case is made from natural aniline leather. Its appearance will change as you use it. [...]
Compatible with iPhone 5 and 5s.
As the report notes, the informational text included on the paper insert is similar to that seen on other Apple accessories, and the "iPhone 5S Case" name printed on the plastic packaging matches the styling seen on an alleged leaked box for the device itself.
One questionable aspect of the paper insert is the use of a lowercase "s" in "iPhone 5s", as Apple has traditionally used a capital "S" when printing the names of its "S-model" iPhones in plain text. The packaging itself also appears to be rather large considering Apple's usual standard of minimal packaging for its products.
Apple is expected to unveil both the iPhone 5S and a lower-cost iPhone 5C at a media event beginning in just a few hours.