NASA World Wind 1.3.4 beta
World Wind developer Randy Kim demonstrated today's build (5Apr06) in Santa Barbara, and it seemed pretty stable. I'm running beta 2, which is several days old, and it has performed normally. The 1.3.4. updates are discussed in an earlier post. I do not think it is on their formal list, but NASA also added a line/arc measuring tool.
Visit the discussion at the World Wind forum for information (and downloads): http://forum.worldwind.arc.nasa.gov/index.php?showtopic=6362
Issues and bugs for 1.3.4 are being tracked at:
The Mars THEMIS imagery used by World Wind 1.3.4 is stunning. No reason to wait for Google.
On a different note...
Google Earth API:
The blog Let's Push Things Forward has a few notes and links concerning programmatically accessing Google Earth.