The purchase of enterprise social network service Yammer by Microsoft may finally be the trigger - and the catalyst - that will kickstart the next step in the company's evolution in the business/enterprise arena.
With Yammer, Microsoft has a total of five communication, collaboration and sharing tools targeting anything from Fortune 500 firms to individuals and everything in between (six if you count Office 365) and it will be a massive challenge to bring them together into a single differentiated service in the (very) long run.
Interestingly, Kurt DelBene, president of the Microsoft Office Division, mentioned Sharepoint, Office 365, Sharepoint and Skype but not Lync in a post on Technet.
As for Windows Live, it still remains Microsoft's biggest virtual online community with a total active user accounts of more than 330 million members at the last count, still a firm favourite amongst business users and one that simply cannot be ignored.
So here you have the pieces of the gigantic jigsaw that Microsoft needs to bring together. A single unified communication freemium solution (free for consumers, paid for for businesses) would make sense and eliminate any existing duplication/overlapping.