Just read this on the Google blog:
Google+ users already use Hangouts to create intimate onscreen experiences—with family members, prayer groups, even people with certain medical conditions. But sometimes you want to speak to a large audience, or alternatively, view as a spectator. In these cases a public broadcast is what’s needed, so today we’re introducing Hangouts On Air.
The setup is simple enough: just start a normal hangout, and you’ll have the option to broadcast and record your session. Once you’re “On Air,” up to nine others can join your hangout (as usual), and anyone can watch your live broadcast:
We’re starting with a limited number of broadcasters, but any member of the Google+ community can tune in. In fact: we’ll be hosting our very first On Air hangout with will.i.am on Wednesday night, September 21. For more information visit will.i.am’s or my profile on Google+.
This looks exciting and would be a great (and free) alternative tool to use as a conference or lecturing tool. I’ll try this out when I next give a conference talk. Tune in!