Hello Robert and all: yes, preparations before-hand and having a helper is key especially when people are still getting used to SL and the its audio facilities. Perhaps we need to think about competencies for SL-Faciliator (Moderator? or presenter?) and the competencies for the Technical-helper. Also, how can the various communication modes - IM (individual or a small group communication), chat (broadcast), gestures, and audio be effectively combined before the actual session (for set-up) and during the session.
In some large-group SL sessions, I have come across another role: 'guide' - who welcomes you and directs you to the right 'place' for the event or gives you a note-card with the schedule of events- very much like a registration desk at a conference.
So I think that there are other 'roles' (and their competencies) in virtual worlds that need to be considered in addition to the moderator role. Thoughts? Thanks.