"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Snow Leopard to Add 4-Finger Multi-Touch Gestures to Original MacBook Air
The latest Snow Leopard developer seeds, however, reveal that Apple will be adding support for these gestures to these "1st generation" multi-touch trackpad devices. Based on reports, this functionality has finally been added for the original MacBook Air (and presumably the early 2008 MacBook Pros).
The original MacBook Air was the first Apple laptop to incorporate a multi-touch trackpad when it was introduced in January 2008 and the MacBook Pros quickly followed with multi-touch support in February 2008.