The rumors were true: Microsoft is indeed buying business-centric social networking site Yammer for $12 billion  or $200 million more than early rumors indicated A presumably pleased Microsoft CEO Steve Ballmer said in a prepared statement that “the acquisition of Yammer underscores our commitment to deliver technology that businesses need and people love” and that “Yammer adds a best-in-class enterprise social networking service to Microsoft’s growing portfolio of complementary cloud services