Find out the basis of the changes to Bing at the Microsoft Research site:

http://research.microsoft.com/apps/video/default.aspx?id=139298

Video is somewhat long, but NOT boring, so download the Video or Zune and use the speed setting to speed up the video to 1.4, that way it will save you time.

This is an interesting lecture about how the Bing Search and any search engine works.