Yammer piggybacks on the popularity of Twitter. Its stated goal: help companies and organizations become more productive through the exchange of short (140 characters) frequent answers to one simple question: “What are you working on?”
Anyone in a company can start their Yammer network and begin inviting colleagues. Network privacy is obtained by limiting access to people with a valid company email address. Founders are former executives and early employees of PayPal, eGroups, eBay, and Tribe.
I’m the fourth member of the University of Washington network. Care to join? [You’ll have to use your UW email address.] If tweets (erh, “yammers”?) are marked with the #MCDM hashtag, it will be easy for the group to have a more private space than on Twitter. Only other members of the UW network would be able to see the posts.
Like most networks, there are positive network effects. That is, the service is more valuable when the network grows, although there could be a point at which the effects become negative. That’s when hashtags will be even more important as a means to set up sub-groups.