The basic concept for this, which we discussed during the working group in Berlin, is that Jan 15, 2011 will be Wikipedia's 10th anniversary, and that a good way to mark this might be to hold events around the world tied together by a special anniversary simulcast, possibly with Jimmy Wales.
This type of thing would be particularly advantageous as an "easy in" for people with limited resources organizing events for that day.
This aspect could be closely modeled on the recent Lawrence Lessig "Wireside Chat", which was simulcast in about 40 live venues, and was even done in OGG format:
http://openvideoalliance.org/event/lessig/
I have talked to Ben Moskowitz of the Open Video Alliance and George Chriss of OpenMeetings.org (cc'ed here), who organized the Lessig "Wireside Chat", and they are both enthusiastic about doing something similar for Wikipedia Day 2011.
http://openvideoalliance.org/ http://openmeetings.org/
Thanks, Richard (User:Pharos)