Google earth's coolest feature (imo) is not the stunning visuals, but rather, the image overlays you can put on it, so you can overlay, subway maps, apartments up for sale, etc.
But in addition, and even cooler than that, is that there's a KML format that you can export from google earth that's an XML file that let's you share and transfer waypoints from inside the app. So if you and I belong to the Stonecutter's secret society, and we need driving directions to our secret meeting place, someone in our group can actually change that waypoint, and we would be updated automatically.
This, I think is in line with their aquisitions in the mobile industry in the last year or so. I think that we'll see some type integration between mobile users, and global knowledge and coordination of places.