Yesterday, T3.co.uk published a story based on statements from Apple that existing MacBook and MacBook Pro owners might see expanded multitouch trackpad capabilites through a software-only update. The statement, however, was inaccurate and resulted in T3.co.uk pulling the original article.
Apple later clarified to T3.co.uk that the new Multitouch Trackpad is indeed unique to the Air, implying that existing Apple notebook owners should not expect to see these features added:
"MacBook Air features the most advanced trackpad we've ever made, integrating the multi-touch technology from the iPhone. This integrated feature is unique to MacBook Air."
This also correlates with disassembly photos that revealed the MacBook Air incorporates the same multitouch controller as the iPhone, which is not found in previous Apple notebooks.
While existing Apple notebooks do have some multitouch capabilities (two finger scroll, secondary click), Apple introduced 3 new gestures (swipe, pinch/expand, rotate) in the MacBook Air. Apple, of course, is rumored to be adding the new advanced multitouch trackpad to future Macbooks and MacBook Pros.