BuddyPress.org

If you’re speaking more about distance education and e-learning, I invite you to look at a few resources on my site:
http://thecorkboard.org/category/instructional-technology/online-learning/

PJ mentions the Scholarpress plugin, which, I agree, is a bit faulty at the moment. But keep track of the Google Summer of Code project that looks to blend Scholarpress with BuddyPress and improve its features as well:
http://thecorkboard.org/gsoc-buddypress-and-sp-courseware/

I think a lot of what you want to accomplish is inherently available within BuddyPress. Meetings could equate to groups. Conferences could be a specific BuddyPress site with some features on or off. I’ve found that looking at BuddyPress – and WordPress for that matter – with a different lens has expanded my perspective on what this software can really do.

~Kyle~