It’s kind of a 3D satellite client for Google Maps, with a ton more cool features. Zooming, tilting, superimposed markers for bars, schools, restaurants, ATMs, whatever.
Larger cities have 3D models of buildings, so you can re-create cityscapes, or see them from different angles.
Part of me thinks Google is actually trying to take over the entire internet, and another part of me thinks that really wouldn’t be so bad.
Crazy stuff, pretty cool. 
Very awesome, except I wish they’d use the USGS maps when they’re better…the resolution in my hometown is craptastic, and Terraserver does a much better job with that particular area.
That said, combining google’s search functionality with satellite maps is awesome.
“Apple Macintosh computers are not supported at this time.”
Apparently they’re not trying to take over the entire internet…
Yeah, this is about the first time ever I’ve been grateful to have Windows at work.
Wanna know what’s cool? I have lived in this little apartment building for more than 5 years. You can actually see my car parked in my spot.
Sweet, it’s the old Keyhole app, which I would try with a free demo every few months with a new email address…
Crap, I need to mow my lawn again.
At least they say they’re “working on it.”
So are these current images? I ask because this morning I left our SUV parked at an angle, half way down the drive way…and that’s how it is showing up on the image. (I never park the car like this).
No. As cool as it sounds, Google does not have a network of real-time high-resolution cameras positioned above the earth.
Then I have gone crazy. Awesome.
Wow. Is. Right.
Incredible. Can’t wait 'til they get more areas in hi-res. Love to see some of places I’ve lived around the world again, up close.
Just amazing.
Give 'em a coupla months.
GOOD:
Yes, it’s cool, fun, and has lots of neat tricks. Great to be liberated from north orientation, and the tilt is good. I like the drawing pin thingy.
BAD:
The photographic library can’t live up to the tech. Tilting a 2-D photo looks just weird. My house ends up as a roof sitting on the lawn. The 3-D cities look cheesy.
Sure. That’s what they’re telling us. What does the CIA have–“Google Spy”?
My house is under a cloud. 
Is this a front end for Google Maps, or something more?
Mine is in the fuzzy part of Toronto. This may or may not be on purpose.
The maps that it downloads seem to be identical to the ones used in the satellite portion of maps.google.com
However, the program provides more functionality: it allows you to overlay layers of things (roads, water features, landmarks, retail establishments, etc.; it allows you to search for directions and then follow the actual roads used in a smooth fashion, turning with the road and such; it allows you to easily tag maps with locations and notes (something I don’t think you can do with the online version). There’s probably more, but that’s what I recognized as different.