This came up on the IRC channel tonight and they posted a link to the related Digg article. Gaia is an attempt to reverse engineer Google Earth and implement its functionality in open, portable, customizable and extendable way.
BUT.. you get this on their web page:
25 November 2006, we've got the letter from Michael Jones, the Chief Technologist of Google Earth, Google Maps, and Google Local search, requesting us to cease reverse engineering and improper usage of licensed data that Google Earth use. We understand and respect Google's position on the case, so we've removed all downloads from this page and we ask everybody who have ever downloaded gaia 0.1.0 and prior versions to delete all files concerned with the project, which include source code, binary files and image cache (~/.gaia).
Nice to see that Google is keeping on the ball with "Thou Shall Not Use GE Imagery Outside of a Google OK'ed Medium". Which is a "Bad Thing" because people don't realize that giving their imagery to Google means you can only view the imagery with what Google says you can view it with. Which takes the imagery out of the public domain.
The project may continue it's life as open source 3D earth viewer with GPS support, but without support Google Earth imagery. We are sorry.
Might I suggest then, coming to a World Wind OS team meeting and joining up with the World Wind Developers? You are re-inventing the Open Source Wheel
Update: Found a screen shot someone posted: