Even though he's talking about corporate communities, this post by Guy Kawasaki also is a must-read for associations. Read it, then ask yourself if your meeting is building community, or taking away from the community you'd like to have around your company, your products, or your association.
Key points to keep in mind: The community has to come from your users/attendees/customers, not you. You have to let it take on a mind of its own, not try to control it or force it to go where you want it to go. You have to have a hide thick enough to support it, even when it's critical of you. And you have to have something that's so great, people will want to congregate around it, interact with it, put their thumbprints all over it, and exchange ideas around it. If you don't have that, nothing you do will draw a community to it.
P.S. For speakers, here's more good from Guy: How to Get a Standing Ovation.
Update: Ben, who always seems to think about things a lot deeper than I do, takes exception to some of Guy's points in this post on Certified Association Executive. I love his objection to the title of Guy's post: "To say you've created a community is like saying you've created a tree." I guess I kind of glossed over that part and just glommed onto the parts that I agree with, but Ben's right. You can only cultivate a community, not create one, and then you have to give it room to grow in its own direction. Which is why I think some are a little leery of the whole community cultivation thing, as I talked about in this post. It's scary being affiliated with—no, supportive of—something you can't and shouldn't control. Kind of like having a teenager. But you have to let it be what it wants to be if you want it to thrive, not what you want it to be.
Another update: Marshall over at MiForum also touches on this idea. An interesting question posed in the comments is, "Is it the 'mass' or the quality of the group that counts?" I'd pick quality over quantity any day, but I'm a firm believer in the power of small groups to get things done.