As for Google Earth and SU (hope this isn't too off topic), the Kmz and Collada SU exports make this easy. Commercially though, providing a Google Earth building modelling service is tricky. There are 2 significant obstacles that I hope Google will eventually address;
Most clients wants to see their properties appear instantaneously and permanently on Google Earth, the 3d warehouse route does not guarantee this, if your model is approved, it can take months to show up on GE and then it is only in "the best of 3d warehouse" layer, it may never appear in the default building layer. Google want quality but surely the easy way to get quality is to make the modelling service commercially viable. Second Life, Twinity, Virtual Earth allow instant upload.
2.Google Earths policy on what is classed as unacceptable advertising is unclear. I cannot find out if it is acceptable for a 3d building to have a corporate logo on the side of it.