World Wide Telescope!
My buddy Keith demonstrated a great new tool called the WorldWide Telescope (WWT)
The 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.
Take a look at the screencast:
Windows Media Player direct link @ WorldWide Telescope Screencast.
You can read more about the Telescope at Keith's full post with links: WorldWide Telescope