In essence all you do is select a city from around the world, make a building with photos Google provide, save the building where it will be reviewed, your building becomes part of the Google Earth 3D layer.
So in short, you do the work and then your building is tied up with the terms of conditions. Such is life, we however just love the access to the imagery and the ability to model, terms and conditions are the subject for another post...
See 'Great Software form the past - CANOMA' for more insights into the simularities, CANOMA is up there as our favorite software of all time.