As expected, Microsoft announced its acquisition of enterprise social networking provider Yammer on Monday for $1.2 billion in cash. Yammer will join Microsoft’s Office division, also as expected, and the team will continue to report to current Yammer CEO David Sacks.

“The acquisition of Yammer underscores our commitment to delivering technology that businesses need and people love,” Microsoft CEO Steve Ballmer said in a prepared statement. “Yammer adds a best-in-class enterprise social networking service to Microsoft’s growing portfolio of complementary cloud services.”

Yammer provides social networking capabilities to enterprises and claims 5 million users and exposure via about 85 percent of the Fortune 500. The service appears to be somewhat similar to the social networking functionality in Microsoft’s SharePoint products, and it works much like a private version of Facebook, where employees can interact and share ideas.

Although the Yammer acquisition has been long rumored, it’s unclear whether it has happened soon enough to impact the Office 2013 family of products, which will include a new SharePoint version. Microsoft says it plans to continue Yammer development as a “complement” to products like SharePoint, Office 365, Dynamics, and Skype, which suggests that deeper integration will need to wait for a future product wave.