Microsoft has launched (an appropriate metaphor this time) its Worldwide Telescope desktop application. You must download the software, but then you're treated to a beautiful array of images and "guided tours" of the cosmos (see screenshots below). Intended for science education, "Worldwide Telescope stitches together terabytes of high-resolution images of celestial bodies, and displays them in a way that relates to their actual position in the sky."

According to Microsoft, the mission of Worldwide Telescope is:

To aggregate scientific data from major telescopes, observatories and institutions and make temporal and multi-spectral studies available through a single cohesive Internet–based portal.
To re-awaken the interest for science in the younger generations through astronomy and new technologies through the virtual observatory of the WWT. This also provides a wonderful base for teaching astronomy, scientific discovery, and computational science.

Here are some images from the application:

Comparisons will inevitably be made with Google Sky, which, as a browser-based tool, is not as immersive. But forget about the competitive rivalry and comparisons for a moment, these are great educational tools -- or just fun for those interested in astronomy.