Google Earth integrated Street View , 3D trees and Historic Imagery in its latest 6th version. In this new version you can explore the streets in 3D. Fly from space to the streets with the Street View. And you can switch to Ground level to see the same location in 3D. You can see the 3D trees all over the world. And it is easy to know when historical imagery is available in the location you are viewing.Watch more videos Of Google Earth 6 here.
If you want to get Street View, Just pick up Peg man (docked along side the navigation controls) and drop him on blue roads he will take you to the road. Once you are on road use navigation buttons or your mouse to go around.To experience 3D trees turn on 3D buildings layer on the left side panel, and click Zoom slider which will take you to the ground level navigation there you can walk under the trees.
Historic imagery is already in fifth version but in the new version it is expanded to all places and will notify you when Historic images available in particular area. You can see the preview of Historic Imagery feature here.
To Download Google Earth 6 visit http://earth.google.com.
To know more about these features go to http://www.google.com/earth/learn/beginner.html.