Five weeks of Yammer experience...
I'm an author in an additional blog for more than a year. As a scientific skeptic blog, we are posting articles or short entries about hoaxes, legends, pseudo-science, alternative medicine, bad science news and similar stuff.
At the begining of this year, we have invited more authors to the group and we have become a micro-community. While we were using Google Groups, after a couple of weeks, it became a serious problem for group members to engage the discussion due to the e-mail over-loading.