What makes Yammer different than Prologue or using Twitter with protected updates?

The blog has been seeing a steady flow of people interested in the TechCrunch50 because of my posting of the rejection letter that I got twice. Someone posted a link to one of those posts on www.techcrunch50.com/2008/blog/2008/07/14/faqs/ and I’ve seen traffic go way up thanks to that one link in one comment. I figured that [...]

Update: I’ve updated the blog with another post about the company that was rejected – The non-profit TechCrunch50 doesn’t want
Dear TechCrunch50 Candidate:
We are sorry to let you know that your company was not selected as a finalist for the TechCrunch50 conference. As you know, we are only able to select a very, [...]