I've been a member for over ten years. The website is dated in content and appearence, but has many great resources. Joining gives you access to the member's posts, but after a while it becomes the same old thing over and over. No harm in joining, but the advantages are not all that useful. There really are no group efforts at barefoot access and that kind of thing, no plans for using strength in numbers or anything like that.
Most of the posts are from people who have been there longer than me who are even older than me....as in over 60!
The FB SBL site is much more active, and is moderated by Dr. Daniel Howell, but is mostly newcomers with typical questions the new barefooter's commonly ask.
Not too many runners participate in the SBL mailing list postings, a runner posted to the forum yesterday and there have been no follow-ups to the post which mentioned Ahcuah's Vibram blog entry.
And no Mike, joining FB SBL does not make you a member of the SBL. You must submit an application first, which is than analyzed by the membershipo committee after reading your essay, and then you MAY or may not be granted membership.
Originaly the FB SBL site was considered a pirate site, and efforts were made to destroy it. Eventually with Dr. Howell's involvement some SBL members began to accept and even embrace the much more user friendly FB site.