I think cosplay is mostly just the japanese equivilant to the various costume stuff you see at scifi cons. It's just targetted around anime and video games. But like many trends in Japan when they do something they go all-out. There's a lot of people in the states who do really good cosplay too these days. There's www.cosplay.com (check out http://images.cosplay.com/list.php?exhibition=28&u=202|40|... for stuff from the last Anime Expo, there's some amazing stuff in there amidst a lot of okay and mediocre stuff :)).