Reflections on a blogs in education project from The Community Engine Blog:
My answer is this. By design, blogging allows individuals to raise topics of interest and create threads of conversation without having to ask anyone’s permission. That was an explicit design consideration for this course; I wanted to know what was going on with students. Bulletin boards tend to be top-down and are owned by one person. Wikis force you to go through a social filter. Others can edit your pages or even delete them.