Jeremy Zawodny points to Keyhole.com in a Web 2.0 coverage post about Geolocation.

Keyhole has a 10TB (that's terabyte ya'll) model (both mapping and geo data); zoom from space down to near street level, calling out points of interest (or even zooming into them, as in this demo -- work safe).

Greg Sterling (and the rest of the Kelsey Group guys) ought to check this out.

Update 10/27/2004: Google buys Keyhole.com
Update 4/5/2004: Google integrates Keyhole with Google Maps