Luckily I have a cousin in the Air Force stationed in Japan right now, so more than likely he will be able to pick up both copies in Japan and just ship em to me. I love having a family member stationed in Japan.
DSi never really got my attention, I already have an Original and DS lite so I see no need for me to get another DS especially if Region Locking comes into play. So thankfully I won't have to worry about that when I get B & W. I might get the English releases as well since there are some Wifi events that I really wanted but missed out on because they were only limited to Japanese copies of Diamond, Pearl, Platinum, HG, & SS.Just remember that the DSi and DSiXL are region locked.
Just flip Black and White each time and you've got my answer. xDI've already pre-ordered my Japanese copy of White. =) I can read Japanese well enough to play with relative ease, so I'm pretty psyched. I'll probably buy Black in English so I can own both versions and so I can play through in my native language, which is more fun.