4 months ago Microsoft made a deal with Facebook to power some of their search results.
Today, if you do a search on Facebook, the web results are powered by Bing and more importantly, carry the Bing logo.
The Bing logo is only shown on the "web results" section of the Facebook results. But this is a major thing for Microsoft, showing their Bing logo on Facebook. It also gives Microsoft insight into the types of queries happening behind Facebook's Google blockade, which is invaluable.
Forum discussion at WebmasterWorld.