I've attended last week a panel discussion with some politicians and around 60 attendees. A feature I'd really like to see for such kind of events in Second Life to handle such events better is available in IRC for over a decade and more already: +V, meaning giving voice.
What's "voice" meaning in IRC? Simple. IRC is a channel based way of online text communication. Some channels tend to be rather large and for many open source projects e.g. it's still a very important way to discuss stuff and things. The channel could be compared to open chat in Second Life.
All men are created equal, but not all are equal in IRC. Every channel has its owner. The owner can per default put all other channel members on mute. This means, they can type what they want, but it's not going to show up in the channel at all. This does not hinder them from sending private messages to others, but the channel is muted first.
If someone should be allowed to speak to the channel, the owner sets the voice flag, +V. This allows then the voiced member to speak to the channel.
That's a feature I'd really like to see in Second Life, parcel based, of course. It would make discussion events much easier to handle. How? Well...
The moderator of the discussion has voice. The discussion members on the panel have voice. The audience after the event started? Has no voice. So they need to direct their questions to the moderator in the room. He decides then, which questions should be asked and either asks them on behalf of the avatar or gives the avatar voice for the time to ask. If then it gets to open discussion the moderator could either give voice to all (bad idea) or make a list of speakers and give them voice one after the other.
This sounds perhaps a little bit on the harsh side, but would really help to handle open discussion events, where not all people are on the civilised side, quite more efficiently and squashes spamming in open chat very well.