.. rumor has it that people were getting carried away with trading (imagine that!) and it was getting in the way of folks enjoying the parks... its a shame, because they had some great pins.. I really would like to hear from someone who knows first hand, and hearing from a cast member there would be great!
I don't think we have to worry about that happening here.. most of the trading nights are well organized in co-ordination with disney mgmt. and disney now has monthly pin events. They have really gone out of their way to facilitate trading in the parks here, providing knowledgeable staff, and areas for folks to trade, it doesn't really interfere with others in the park. (not to mention they are probably making a ton of $$ ;-)
I think some of the Disney stores in Japan will still be selling pins, and many folks use pinpics to trade for japanese pins. hope that helps!
--heather