Check out this podcast about Google Earth from the Where 2.0 conference where GM John Hanke says it was partially inspired by the Earth program in Snow Crash. Fun. He also refers to Google Earth as a "3D virtual world," which of course it is though that language isn't often used to describe it. Very nice to hear it phrased that way by someone at the heart of the project.
Have to update and advance my Brave New Virtual Worlds presentation stuff, but I do want to keep banging this drum: User-created virtual worlds like Second Life are pioneering the media-rich 3D Web, as in Neal Stephenson's Metaverse [from Snow Crash]. Searchable, interactive virtualizations of our planet, like Google Earth, are opening the geospatial Web as in David Gelernter's Mirror Worlds.
The convergences that will happen in the coming years between gamespace stuff and living virtualizations of the planet will be beautiful and important. When do you think avatars will land on Google Earth?
BTW Second Life has opened their mapping API with Second Life Webmap Beta. Bring on the mash-ups!