Scot Hacker is trying to find the right blog for students in a course he's teaching.  Regular readers will recognize that as a concern I've had as well.  I've always had my students keep lab notebooks and I used a blog for my course last year.  This year, I want the lab notebooks online as blogs.  Since the course already uses Slashcode, the journal feature is a natural tool to consider.  There are even RSS feeds of journals, a key requirement.  I think that some students will be taken by blogging, however, and want a more robust tool than the Slashcode journal system.  For that, I'd recommend Radio.