Blogging, in one of its forms, can be a debate held across space and time. I write something on my blog; you link to it from yours and either expand upon it or argue against it; I can respond, others can join in.
What if we did some of that and then met up in person to continue the discussions? That would provide for the engagement and preparation of everyone beforehand, and because the discussions are stretched either side of the meeting event it would be a bit of a long conference.
Count me in.