Google released a plug-in, currently for Windows browsers only, that allows you to embed the Earth application inside the browser. Existing Google Maps mashups can use some of the functionality right away just by adding the G_SATELLITE_3D_MAP map type. Even more exciting is that you can interact more deeply with the map—including camera angles, KML layers, and 3D models—right from Javascript. I’m so eager to go find a PC to play around with this that I’ll let the video speak for itself.

Also worth noting is that Google just released an official Maps API for Flash AS3. Call me a fanboy, but I think my head is spinning.

Google Earth API
Some Example Applications
Maps API for Flash