Did you see Google Earth now has 3D trees? Its pretty cool... and, as the author points out in this article, we expect to see 3D dirt highlighted in a future release.
Gotta tell ya though, flying beats Google Earth for an awesome way to see the world in real 3D. Flying gives you 3D trees, plants, terrain, buildings and clouds. Plus smell-o-vision (one plane I fly gives you the lovely smell of avgas every time you turn right when taxiing), and the feeling of the air. Glass smooth air like yesterday, mostly smooth air like Thanksgiving, or bouncy as all heck like my last flight lesson.
If you want to see the world in real live 3D, with living color and variable lighting and the feel of the air beneath your wings, and watch the kids on the dirt track riding their bikes on the track, hop in a small plane. Preferably a high wing one so you have a good view... and take in a whole new way to see the world in your back yard that you never saw before. I highly recommend it.