http://www.worldwidetelescope.org/
What is WWT?
The WorldWide Telescope (WWT) is a Web 2.0 visualization software environment that enables your computer to function as a virtual telescope—bringing together imagery from the best ground and space-based telescopes in the world for a seamless exploration of the universe.
:) Information above taken from the "What is WWT?" section of the http://www.worldwidetelescope.org/ site.
1 more reason I love Microsoft.
