Microsoft is to acquire business social networking solution Yammer for $1.2 billion, and is likely to incorporate the solution into Microsoft Office and its other enterprise programs.

Microsoft, which also recently acquired Skype, appears set to make business sharing an easier proposition, hinting at plans to integrate Yammer’s technology with Office, Sharepoint, Dynamics (its CRM tool) and Skype.

Announcing the acquisition, Microsoft says it will maintain Yammer as a separate business unit, while integrating it with its own offer. “Yammer will continue to develop its standalone service and maintain its commitment to simplicity, innovation and cross-platform experiences,” the statement reads. “Moving forward, Microsoft plans to accelerate Yammer’s adoption alongside complementary offerings from Microsoft SharePoint, Office 365, Microsoft Dynamics and Skype.”

Launched in 2008, Yammer now has more than five million corporate users, including employees at 85% of the Fortune 500. The service allows employees to join a secure, private social network for free and is often used as a knowledge sharing and team building platform.

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

The acquisition is subject to customary closing conditions, including regulatory approval.

Microsoft was rumoured to be working on its own Yammer competitor, known as OfficeTalk, but that now appears on the back burner according to a case study posted last week which indicate it’s now nothing more than a Microsoft IT demo project.