Microsoft has further vindicated the idea of online social networking as a business tool by purchasing the enterprise collaboration firm Yammer for an estimated $1.2bn.

Yammer, which has often been called the ‘Facebook of business’, claims to bring “the power of social networking to the enterprise”. It allows co-workers to communicate and share information almost instantaneously using Facebook-style newsfeeds.

The move comes as Microsoft tries to expand upon its complementary cloud services and, more importantly, fend off competition from Google for its influential Office products.

The money involved is hefty, but small change compared to the $8.5bn (£5.4m) Microsoft shelled out for Skype last year.

From Microsoft’s perspective, Yammer will be integrated into Office365 among other applications and will be cloud-based only. As Microsoft CEO Steve Ballmer told the Press Association: “Think of Yammer as a fundamental part of our Office family”.

Whilst Yammer does not have the sheer numbers of many of the mainstream social media networks, it does have an impressive range in the corporate sector with employees at 85% of the Fortune 500 influential organisations list signed up.

The service is currently “freemium”, in that it offers a free service alongside a $5 per month premium deal.

Tools like Yammer, and competitors like Salesforce’s Chatter and Jive Software, have seen strong growth over the last couple of years, as employers realised that people are more likely to collaborate and innovate using familiar social networking user interfaces.

Yammer founder David Sacks, in a blog post entitled “Yammer’s Next Chapter”, said that their goal “was to massively accelerate our vision to change the way work gets done with software that is built for the enterprise and loved by users”.

Microsoft said it would continue to develop the service as a standalone platform, as well as integrating it into SarePoint and its other collaboration tools.

Microsoft CEO Ballmer added: “The acquisition of Yammer underscores our commitment to deliver technology that businesses need and people love”.

So it’s another happy marriage to swan off into the sunset. Have you used Yammer, or any of the online collaboration tools? What will you be looking for from Microsoft’s influence in its development?