http://wwtelescope.com/

   The WorldWide Telescope (WWT) is a rich visualization environment that functions as a virtual telescope, bringing together imagery from the best ground and space telescopes in the world for a seamless, guided exploration of the universe.

WorldWide Telescope, created with Microsoft's high-performance Visual Experience Engine™, enables seamless panning and zooming across the night sky blending terabytes of images, data, and stories from multiple sources over the Internet into a media-rich, immersive experience.
  
http://scobleizer.com/2008/02/27/what-made-me-cry-microsofts-world-wide-telescope/

Scoble Reviews its impact