BarCamp borrows some devices from OpenSpace: no set agenda, collective creation of the conference schedule on day 1, "whoever comes is the right people", and more.
Some BarCamps actually are run "in OpenSpace" as we say: you can see a great video of the OpenSpace at recentchangescamp.
OpenSpace is another great collaborative way to hold a conference, in use for over twenty years! You can read more about it on Larry Peterson's site http://www.spiritedorg.com/open.htm . Larry is one of the most experienced OpenSpace facilitators and trainers in North America.
one blogger's view of classic Open Space
Some pictures.