First, we "opened the space" with all conference participants, whether they intended to stay in OpenSpace or not. This allowed people to flow in and out of the OS event, confident of the rules and free to fully participate if and when they wanted to.
Second: inadvertently, we found ourselves in a wonderful room layout. The large room had two entrances, on south and east sides of the room. The tutorials were taking place on the south, and the coffee was beyond the east door... inviting non-OpenSpace participants to wander through the space. I think that two doors for the OS space may be a key pattern: allowing curiousity without committment :-)
I noticed something interesting happening at one session, and wrote it up for my publication, InfoQ.com. I interviewed the participants at one session to better understand the dynamics of a session which included both total newbies and very expert participants:
Experience Report: Beginners and Experts All Benefit in Open SpaceEnjoy! (We did! :-)
Agile events are receiving an influx of novices - should new conferences be organized for beginners? A report from XPday suggests that mixing up expertise levels creates a valuable experience for all.