I’ve never used Yammer but apparently 40,000 companies do so it’s something to take seriously. Yammer is meant to make companies more efficient by allowing you to create a microblog for employees and it can act as a source to track projects, invite users and keep conversations centralized. it’s also secure and access is limited by email domain. Today they released an Outlook addon (so don’t be shocked if you hear MS is buying them out:)) and with that they also released a Windows Mobile application (to go along with their existing Blackberry and iPhone apps). So that means most people, whether they are in or out of the office, can be up to date on the latest office events. And it’s free..
The download is available here.