Google Earth for the iPhone is now available. I’ve been playing with it in on my iPod touch this evening. My instant reaction: Google has absolutely nailed the interface — Multi-Touch was meant for Google Earth, and using the accelerometer to provide tilting was inspired — but it’s not as feature-complete as the desktop version, as you might expect from a mobile implementation. Only five layers are supported — and street data isn’t one of them. (I suppose you can get that from the bundled Google Maps application.) I anticipate that more will be added to this application in the future.

Detailed reviews of Google Earth for the iPhone: CNet, Google Earth Blog, Ogle Earth, RenaLId, TUAW.

See also Google’s introductory video and user guide