I've heard through the grapevine that the Japanese community is concentrated around a handful of smaller groups and that there's no real monolithic competitive entity for the Japanese like Smogon is for the English community. Dunno how accurate that is though.
I've heard similar things, and it reminds me how fortuitous we are to have smogon, current weak VGC coverage/support or no. I don't want to go all e-historian, but six or seven years ago we were damn spread out ourselves(even more so 10 years ago) between various websites, from general monstrosities like GameFAQs and IGN to smaller Pokemon specific sites; we were spread even among simulators later with the "rivalry" between NB and the bots until we switched over for the better interface. Things are kinda spreading out again, but the size of Smogon has been great for communication. If nothing else, everyone at least has an account here, and we all play on the same sims(which is spreading us again too...) and servers... we have a bunch of different banners, but when it comes down to it these events make it pretty obvious we're really all part of the same community here with the whole English speaking community Smogon seems to have come to represent.
It is probably the sims that unite us more than anything, but even with all our reps being [USA] the community extends to most of the English speaking world, I think - to Canada and the Brits, obviously, but also to France and Germany and Latin America and all the other countries we have representatives from. I'm a big fan of the idea that you get better by playing better opponents, and frankly our rivalries probably help us there(and Pokemon is probably always going to be too cliquey to avoid them anyway).
I think the reason I'm rambling is just to say I think these events give interesting perspective... I'm sure we'll all be at each other's throats by Nats '11 again, but now is a good time to remember that when it comes down to it we're all on the same team. That's why the country is listed, eh? It'd be huge for that cumulative community if any of the four won, I think. We're all rooting for all four of you.