I've spoken before about the possibilities of weblogs: they can be used as journals, as community builders, as portfolios. We use them for the second two, mostly, here. But I've found another good trick that I like, and I'm trying to perfect it. The student group weblog. Some of the ones my students did come off of the Newstalk 052 weblog. You will notice that some people happened into some of them and commented on them, which is not unusual. They wrote about news events and gave their opinions; they entered the conversation. More power to them!
A colleague wrote in to a discussion board a comment that I've been mulling over: "if you want them to really be free with their opinions, let them take assumed names..." I think this is good advice. Not that we should require it, only that we should allow it.
As for contributing to the weblog scene itself, we should require that. Participate! It's a community, just like a class: what good does it do you if you're just aloof? I think everyone should grab a handle on it and make a good page. It can be done...