Seems Microsoft is continuing its push at Facebook. Last year, Microsoft became the banner ad supplier for Facebook in the United States. Today they purchased a 1.6 percent stake in the company for $240 million - making the whole company worth $15 billion - and announced they will now handle distributing banner advertising for Facebook outside of the United States, the New York Times reported.
If Facebook were to add a web search box into their interface the search number could well grow Microsoft's percentage of searches significantly.
UPDATE: For more on the story, see Microsoft Named Exclusive Advertising Partner for Facebook on ClickZ News, or one of the hundreds of accounts on Techmeme.