Keir Clarke has developed Star Viewer using the new 'sky' option in the Google Maps API:
With Star Viewer you can watch a number of astronomical videos embedded on a map of the night sky. A number of the videos are from the Hubblecast series produced by the European Space Agency. The Hubblecasts feature news and images from the NASA/ESA Hubble Space Telescope. In addition to the videos the map placemarks give way to a number of other amazing images from Google's huge tileset of merged telescope images and that are also viewable in Google Sky!