The Microsoft-Yammer acquisition is a go, with a $1.2B pricetag

Microsoft has officially removed the final veil to reveal its planned acquisition of Yammer for a tidy $1.2 billion in cash.

We’ve been hearing rumors about this deal for a week or two; the Redmond-based Windows maker has now issued an official statement on the acquisition, complete with a quote from Microsoft CEO Steve Ballmer.

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

Yammer will become part of the big, happy Microsoft Office family. All things considered, the deal makes complete sense. The enterprise is Yammer’s target audience, and it’s also one of Microsoft’s sweetest sweet spots.

In fact, just a couple months ago, Yammer did a little acquiring itself, snapping up startup OneDrum to better integrate with Office.

Yammer had 5 million corporate users the last time we checked in with the team; those clients include employees from more than 85 percent of the Fortune 500. It’s gotten to that point by growing in a viral, bottom-up way; now, with a Microsoft takeover, it’ll also be available as a top-down solution.

The company also recently rolled out Universal Search and more third-party integrations.

Yammer was founded in 2008 and has taken a total of $142 million since the beginning of 2009.

And for those of you who fret about Yammer’s product evolution post-acquisition, take heart. “Remember that other expensive acquisition that Microsoft recently made?” asks VentureBeat guest writer Eric Jackson in a recent post. “Despite critics wailing that somehow the innovative communication network would be ruined once it entered into the Redmond giant’s portfolio, Skype has maintained its independence. Now, think how useful real-time chatting capabilities would be inside of Yammer for a large enterprise spread out across multiple office and locations.”