When Apple introduced the new MacBooks, MacBook Airs, and MacBook Pros in October, they also introduced a new four-finger multi-touch trackpad gesture that allowed users to easily switch between applications (swipe left/right) or invoke Expos (swipe up/down). While it's long been known that the original MacBook Air and early 2008 MacBook Pros were also capable of detecting these 4-finger gestures, Apple has not yet announced or provided software support for the feature.
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.