Since today is 1st april, I doubted if this was for real until I grabbed my 3D glasses. I couldn’t believe, it is 3D for sure. The depth of the 3D field is not all that huge, but when cruising in fullscreen, gives a delightful experience.
So this means google used Stereoscopic Cameras while shooting in streets, and kept it hidden until now.
Note: 3D without Glasses is a future thing, right now you need Anaglyph 3d glasses to view the above content. These are cheap paper glasses available at ebay, and local crafts stores. You can even make your own.