Microsoft's description of itself as a "devices and services" company involves delivering new products faster (like new features in SharePoint several times a year), as well as charging for subscriptions rather than licences. Can Yammer teach the software giant some new tricks?

"We've helped Microsoft spin up a team internal to Office that is focused on product driven analytics," Pisoni told us. "Everybody realises that it's not just about delivering more value any more; if you can't ship quickly the data is almost useless."

Software has to change this fast because companies have to change at the same rate.

"People are using Yammer to work in less structured ways," Pisoni explains. "Companies used to have the leisure of organising in really fixed ways and assuming the world wouldn't change so fast that that wouldn't work well.

"Now they're realising that in order to spot opportunity fast enough and to react fast enough, they have to be much more flexible in how the organise.

"The promise of the enterprise social network is that it lets you organise more organically, find the people that can help you or surface information that's relevant to people."

Doesn't changing things too often get disruptive and inefficient? To Pisoni, efficiency isn't an advantage.

"Companies are driven towards efficiency but they don't calculate in what we call the friction for change. If you make something more efficient you may make it harder to change. It's efficiency versus throughput - if you're focused on efficiency you could actually get worse throughput because things need to change.

"We want to focus on throughput. Who cares about efficiency?"

Looking forward to how Yammer's market may change, he says enterprise social networks could be very different in two years.

"Right now, when we think of enterprise social networks we tend to think primarily of the web interface. But we're pretty sure web is going to be less important than it is today as mobile devices become more important.

"Mobility gives us all these sensors like location and calendar. If the goal is maximum utility of information and organic organisation then the thing we have to improve is getting you the right information when you need it."

As usual, what he's most certain about is change.

"There's a million theories about how this is going to happen, and it's probably not going to be any of the ones we think of today."