Mark
CreativeMountainGames.com
I'm going with the theory that RPGA D&D is most of the D&D being played at game conventions these days.
Maybe most of the current edition, anyway, as I have seen much of PF, 3.5, 1E and even some (O)D&D being played at the shows I attend. Can't say I see much, if any, 2E, FWIW. I know of at least a couple of 4E games that were run at Gencon but off the books, so to speak (just check the EN World Gencon forum for details). I wonder if 4E inspires more people to play than to run games, as far as that goes. Is running 4E for strangers not as rewarding as elsewise, perhaps?