In an attempt to stay relevant, Microsoft will ship its next version of Office (Office 15) with Facebook IM. “For Office 15 we're building new products to deliver integration of instant messaging/presence with social networks such as Facebook,” the company wrote in a job posting. This partnership between Microsoft and Facebook is not only seen as Microsoft's attempt at staying relevant, but also keeping a common enemy, Google, at bay.
Now to come with Facebook integration
The idea behind integrating Facebook IM is maintaining social contact while working. It's based on Presence Data, which distinguishes itself from regular Instant Messaging which is basically a way for users to see who they know that can answer a particular question at any given time. Microsoft has previously tied in with Facebook on Docs.com, their online version of Office. The site hasn't necessarily been widely adopted but when Facebook groups had first been released, Docs.com supported it as well.