That's what Stephanie Downs at ConferZone says in this post on her blog. And she makes a pretty good case for it, except for the fact that all her sources have a vested interest in saying virtual events are having a growth spurt.
I've yet to experience an online trade show, myself, something I really should do before saying anything about them. But I will anyway. I definitely can see the time- and money-saving benefits, but, my innate geekiness aside, I am and probably will remain a face2face gal.