"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Apple Gives 2nd Generation iPod Shuffles to Employees
The 2nd Generation shuffle just began shipping last week, after being announced in September.
Apple previously gifted iPod shuffles to many of its retail employees back in January 2005 as a thank you and incentive.
The first customers have already posted photos of the newest iPod, and Apple has posted a short FAQ.