Its very impressive indeed.
Have you seen "Earthmine", its a newer project that at first glance looks same as Google.
But they use very very high tech cameras and scanners, to the point in all there photos and images you can get measurements of buildings and even measure the size of your front living room window online!
Its currently not public, but being used and trailed by agencies and businesses etc. Its also going to be interactive. The theory being you could say, walk around a city and click on the supermarket to do your online shopping. Then step back onto the street, walk down to the post office, click on it and go inside to complete some application forms. Walk down to bank and pay some bills. You get the idea, i total virtual world scenario.
Heres a shot of an Earthmine image, the resolution and detail is so high they say you could see the colour of a cats eye sat the other side of the street. And this example shows how the measurements and height of buildings can be checked.
With such incredible detail there will be privacy issues, but imagine the usefulness of such a system! Council officials could go check the size and height of a new shed you've built online!?
EDIT:
www.earthmine.com