This blog entry about using wikis at face-to-face events to create an ongoing dialogue is interesting to me. The piece describes the use of a Wiki to have participants at a workshop create, on-the-fly, a book about the event. There were over 400 pages of content on the Wiki at the end of the event and then the workshop organizers assembled that into a book with ongoing collaboration of the participants. The O'Reilly folks use a wiki at their conferences, but I'm not sure how many people use it after the event.