Some time ago I predicted that Google Earth will become the ultimate game engine. To quote, I said:

there is bound to come a (fly) game in Google Earth.Think of that, Google Earth as your browser (think place instead of a textbox as an entry point for your searches), Google Earth as the base for a CMS, Google Earth as a gaming platform.

And... indeed. There is now a flight game in Google Earth. See marco-za.blogspot.com.

It would be great. Google Earth as the Graphical User Interface of your Operating System, a multiplayer game engine, the base for searching data (the browser) and for ... life the universe and everything.