Below is a sneak preview of Microsoft's WorldWide Telescope that a lot of people have been raving about. The application is planned for release in the spring sometime.
On this evidence it seems to be similar to Google Sky with the ability to add tours. Anyone who knows kml can knock together a tour for Google Sky. However the video seems to suggest that a six year old could build tours for WorldWide Telescope.
If you can't wait for WorldWide Telescope then check out our Star Viewer