Mike,
I think what you may be talking about is actually a "community of practice"?  The concept developed by Etienne Wegner (http://www.ewenger.com/) that he defines as "Communities of practice are groups of people who share a concern or a passion for something they do and learn how to do it better as they interact regularly."
This would be engaging for the linkedin group and can take different "shapes" depending on the needs of those in the community.
Great thought provoking post!
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