For ongoing course use, I've thought about creating a class blog. That would be an easy way to organize course announcements and updates, and it would be more interactive, so that students could continue to discuss course-related issues outside of class. Blackboard now has a Blog Tool, but I haven't tried it out yet.
The issue of blogs vs. Blackboard is taken up today in the Chronicle of Higher Education. A scholar is quoted as urging the use of blogs rather than Blackboard as a way to open up access to course content. Blogs are potentially open to anyone on the web who wants to read them. But this is not a good thing if you want to restrict access only to course members, so that students can post comments more freely without having to worry about making a public record of their untested ideas. But blog software, at least the program I use, enables you to limit access. If I use Blogger rather than Blackboard to bring more interactivity to a course site, I will set it up so that it can only be viewed by members of the class. One advantage to a blog is that I could post via email when I don't have either the time or computer access for a Blackboard post post (e.g. while traveling).
I would be so interested to know about ways others are bringing web 2.0 into the classroom. Creating on-line resources and discussion opportunities strikes me as especially useful in legal history classes. There is only so much we can cover during a class period, and a website or blog enables students to go beyond that, and explore on their own, following links to on-line resources. The biggest barrier to doing this is no longer the technology, since it is now so easy to use. It is the usual one: having the time to do the initial work to pull something together.