I have been following this week's Vancouver Company of Friends mailing list discussion about careers and I came to the following mini-epiphany:
For most situations, blogs are better than mailing lists and bulletin boards because links are native to blogs rather than being bolted on afterwards as they have been for mailing lists and bulletin boards.
Most bloggers link to the original source when they quote something. In mailing lists and bulletin boards, people are forced to quote inline and typically don't reference the URL of the email (assuming there is a web archive of the list) or website because email just isn't suited to linking. This means that unless you read all the messages in a thread, you can't get the full context. Instead you get what was quoted.
Although blog threads are distributed among many blogs, the cool thing is that by clicking on all the referenced blog posts, I then land at that person's blog. Then if I want get a sense of what the person is an expert in and who they are, I can read the blog archives.
This is impossible (or very difficult) in mailing lists. If you are on an active list and say you post 10 emails, then your body of work in that list is dispersed and hard to follow and find.
Another example is the 300 or more trackbacks to Mena's post about the new MT licensing. I read about 150 of these. Because everybody who did a trackback has a blog, I could come to my own conclusion about the credibility of the feedback by quickly reading a few of their earlier posts to see where their biases are. I couldn't do this with a mailing list discussion.