The weekend of September 30th and October 1st will be a big one in the Information Architecture world:
Perhaps there could be some sort of video hook-up between them? Or at least some internet conference / live chat during the hours when both sets of attendees are awake and coherent? Using this meeting planner for Berlin and Sydney, the best time appears to be:
The Aussies could end their first day by helping the Europeans kick off their first day.
Depending on how late people would be up (drinking?), there are other possible times. But could the 2 events sync up?