Real skydiving involves jumping out of a plane and the potential for violent death. Google Earth skydiving involves neither of these things, but as long as you're a bunch of crazy Japanese guys, it still looks wicked fun.
All it takes to skydive on Google Earth is a projector, some blue tarps with clouds spray painted on, a suspension system, and a bunch of nutballs with giant fans and fire extinguishers to help set the mood. From the initial height of this jump it looks like the starting altitude was somewhere up around the International Space Station, which brings up some interesting possibilities: Google Earth does Mars too, so you could virtually fly in a wingsuit down the slopes of Olympus Mons with this setup.
This project was part of Google's Demo Slam, and there are 58 other vids showcasing Google tech used for weird stuff, many of which are almost, but not quite, as awesome at this one.
The video is right down below, and it's a must-see.