In order to zoom in or out, they can instead move their hands down and up. A slight wave turns the globe, and they can mimic a plane to soar over terrain--flying, for instance, under the Golden Gate bridge or over a mountain range.
Support for Leap Motion in the desktop version of Google Earth will go live today, Earth Day, but only about 10,000 developers currently have access to Leap Motion technology. Controllers go on sale for the rest of us next month.
[Spinning Globe Image: Flickr user Gabriela Pinto]