re: Yammer And The Freemium Trap
I can understand where these concerns are coming from, but in my own experience, Yammer's Freemium offering was a huge benefit. The model allowed us to run Yammer in pilot mode at no cost when we were considering an Enterprise Social Media platform for our business (and the momentum our Pilot created carried us forward through a successful Premium rollout).
There are a lot of technologies like this out there that can be misused: personal cell phones, iPads, email, photocopiers, Facebook, Google+, Dropbox, YouSendIt, etc. As a technology leader, if you discover that a significant segment of your business is deriving value from an unsanctioned technology offering, you've uncovered an opportunity. Either you have a corporate alternative in place and you have a chance to migrate these users into the corporate fold, or you have stakeholders and sponsors for a new project to help make your business more successful. The business landscape today is full of opportunities like this for us to do better as technology leaders.