Being a multi-billion dollar Global Tech giant has its advantages. One good thing Microsoft has done is pour a ton of money and resources into Research. A recently announced research project will be released this spring and looks VERY cool!
Microsoft's WorldWide Telescope uses their "visual experience engine" to seamlessly pan and zoom across the night sky. My explanation probably won't do it justice, and it isn't out yet -- but there is a nice video demonstration on a TED Talks video.
Here is a MSNBC article on it and here is the Microsoft site for WorldWide Telescope.
Now...I'm still a Google fanatic, and love Google Earth and the 'sky' function inside of Google Earth--but this new Microsoft app looks to be a strong contender. With the Google/NASA partnership I'm sure we haven't seen the last of the cool apps/features from Google Earth.