From previous experience (last year's con) I'm expecting the bulk of the audience to be in their 20s to 30s and generally scientifically literate. This, of course, doesn't rule out the possibility that some will still be HBs.

I've been instructed by the organiser that I *must* use visual aids (she's paranoid about people droning on for half an hour and boring the pants off people) so I'll probably want to use a Powerpoint presentation of some sort to show relevant piccies.