Adam Pisoni, the CTO of Yammer, has a very people-centered view of how work media (enterprise social networks) are being adopted:

Collaboration vs. Competition: How to Drive Innovation, Intel Free Press

People have this basic need to find other people who are like them, to feel there’s value in what they’re saying and doing. The revolution of social media is that it was the first communication tool that supported an infinite number of people talking at the same time. The telephone and telegraph was great for one-to-one communication. Email revolutionized that by adding one-to-many. Social networking is really the first many-to-many.

Yammer exists because companies weren’t offering these [many-to-many] communication tools to their employees, and employees really wanted efficient communication that lets them connect to each other, wherever they are, whenever they need to.

The rogue adoption model that Yammer has successfully championed — where individual users sign up for the service using their corporate email address and later on the company ‘claims’ the account for a fee in order to get access to premium features and other controls — is certainly in line with this viewpoint. Like Get Satisfaction — whose rogue customer support model caused many companies headaches — Yammer’s adoption model annoys management in some companies, who may feel like they are being strong-armed into paying for an account. At the same time, I agree with Pisoni that it is unmet demand for a work media solution that drives this rogue adoption in the first place, or more specifically, the desire of users for a social space for ‘work talk’. And if the company won’t provide one, the people will pick one.