The venue is Gathertown, which works surprisingly well. OK, so I can't easily grab someone I see at a distance and talk to them, because I don't know what their intention is (are they going somewhere or just mooching around?); then again, no-one can buttonhole me and press me into a conversation when I'm just about to go make a cup of tea, either.
One thing we didn't have that real conferences have is the runner: someone with a microphone who hands it to whoever is next in line to ask a question in the Q&A session. I guess this could be simulated by an NPC under the control of a moderator, but it might as well just be a limelight (which is what old theatres used to shine on a member of the audience to pick them out): if the limelight shines on you, you get to speak. I expect something like this will be implemented within a few months if it's not available already.
This was how Gathertown looked during a student presentation at 2pm:
There were 81 people there, which is more than I ever get in my lectures.
It's also more than the number of people I see in Crowfall, but let's not dwell on that.