There is all the difference in the world between blogs and paper diaries. The difference comes in being able to create communities.
I had an interesting exchange with Mark Fichman, a noted social scientist at Carnegie Mellon's Tepper School of Business. He asked me how something like “The BIT320 Distributed Learning Blogosphere” differs from diaries with email added on. Unlike Dave Winer's response for web logs in general, I think there is all of the difference in the world.