A teacher blog article comes from the person first, and the teacher second. Discussion boards are designed around topics. Blog environments are designed around people.
This idea of putting the person into a blog, and therefore, into the discussion that ensues, is a truly important one. How much of our professional life is spent without the person being present? In "professional development" situations we sometimes have a tendency to tune out entirely. But that isn't how blogging works. We are present if we blog. And we are present when we comment on the blogs of others. And when we are present, we can truly learn from one another and from ourselves.
As I write this, I just got through talking with Anne Davis about my blogging problems. This is just one example of collaboration that has arisen out of blogging. I feel sorry for anyone trying to teach who doesn't have blogging friends to bounce ideas off of. I couldn't do it without you all!