Bruce Eckel covers what Open Spaces are how they are run, and resolves many misconceptions about 'Unconferences'. 10 seconds into this video, and you'll see the first of the mechanics for how it works, as well as lessons that Bruce has learned in doing UnConferences.
Even though this video is titled, "Open Spaces" - it really is about running an Unconference, step-by-step, using Open Space concepts. The two concepts are a bit different.
Open Space tends to be about developing actions as take aways focused around a central theme or issue. It is not necessarily focused primarily on learning and exchange, although it CAN be, as I will be demonstrating in a learning & dialog focused 30 minute Open Space demonstration/learning event at a panel/open space combo event at our April, 2012 session for the Assn. for Change Management Practitioners in Las Vegas.
UnConferences are about learning and dialog, in an open, self-directed format where participants co-create & co-own the outcomes.
Here's a collection of UnConference videos, interviews, and how-to resources that you might find useful, as deemed by my perspective as a facilitator and change strategist/organization development practitioner:
Two views of What is an UnConference? Brief video
Show and tell, photos of an unconference in action.
Video I (part of a series) of healthcare & teamwork UnConference in action.
How to prepare to attend an UnConference, especially if you might be facilitating dialog in an UnConference session.