Let's look back a few years... Then Nintendo DS system itself was announced in Japan before it was in the US.
It was released November 21, 2004 in the US, and December 2, 2004 in Japan. Europe didn't even get it until March 11, 2005!
I'm pretty sure that's what it's going to mean. I don't question Nintendo anymore. There must be a method to their madness.
It's also possible since it's going to be released in Europe before the US, we're all going to be glued to our computer screens learning the English names of all the new Pokemon, or they'll officially release something to do with it. (or they're recommending when to start camping out in line...)