The event had about 40 participants and 17 talks in 4 hours, and it was successfully run by the participants.
As you may know, "conference" requires its host to arrange the program *much before* the event starts. As opposed to that, "unconference" doesn't.
"Unconference" is filled with many short talks, typically 10 to 20 minute ones, which need to be arranged at beginning of the event, and running multiple (two or more) sessions at the same time to give a chance to participants to find a topic they are interested in.
What we did and what we saw there.So, I started the event with saying this:
"Welcome to *the most unprepared event* we've ever had! :) Now is the time to start arranging our program. Please write down the title of your talk on the post-it note, and put it on the white board."