And I'm sitting on the front row, shoulder to shoulder with several techies, so hell no I didn't attempt to record anything.
Yes this would have to be something to be planned before hand, so that you already walk in ready to record. There are tons of cheap gadgets that are undetectable.
I actually just bought a shirt button camera, which I am going to use for something... ;) ...more to come on that. I had previously bought glasses which have a hidden camera, but I found them to be too unnatural and you could see the record button on the side if you looked close.