"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
First 27-Inch iMac Deliveries Now Arriving
Apple announced the redesigned iMac at its media event on October 23, but noted that the 21.5-inch model would not begin shipping until November with the 27-inch models following in December. Apple began taking orders for both sizes on November 30, with the 27-inch models seeing 2-3 week shipping estimates at that time.
Availability remains tight as Apple reportedly works to achieve acceptable yields of the new display assembly, which laminates the display directly to the cover glass. With the larger 27-inch displays proving more difficult to assemble than their smaller siblings, supplies of the 27-inch iMac models are particularly tight.