"Discussion Lists --
Great for this is me announcements, What do you think about this type questions, or I'm having issues implementing such and such. If archived online can be indexed by search engines. :-) Check out http://www.mail-archive.com/
Not so good when restricted to a single topic. Or when an online archive isn't present. The list tends to stagnate.
Pretty good for how to posts, tips and tricks, and tracking comments. Indexed by search engines :-) Here is an example of a highly used forum - http://forums.gentoo.org/
A royal pain to find useful information, when the base structure is disorganized. Or when the comments on a single post goes on and on for several pages. http://forums.gentoo.org
Twiki / Wiki's --
Really good for how to posts, best practices, editable by a large number of people etc. http://gentoo-wiki.com/Main
Can be over kill for static content. While you can edit the page you can't really place a comment outside of the discussed area. You have to make a new entry in the posted page and anyone can remove your comment.
Defiantly fits the news post type role and people can comment. Blogs can also be used to give a recap of the more interesting dialogs that occurred during the week with groups using any of the above methods. Could be a good way to point people to your more user active areas.
Doesn't really foster an active community. Seems to foster a passive community....