I'm listening to a demo by a company called Vello. It's a phone conferencing service, but doesn't require dial-in numbers or passwords. If the organizer of your conference call has your coordinates (Entourage importing, yadda yadda), you can just dial in from your mobile phone, and it can automatically "drop you into the room where your conference is happening."
So we talk about virtual "rooms" where you talk to people. Since meetings happen in real space, it makes sense to use the term.