The interest in Nintendo's systems have been much greater in the U.S. than in Japan since N64 came out. I'd guess that would explain much of the Japanese launch.
All I know is every major .dot company that's offered a GC bundle so far is selling out within minutes of offering it. If you got to a B&M the morning that it's offered for sale, I'd say you have a decent chance (remember, on 11/18 we're nearing Thankgiving & the Black Friday Christmas rush). If you wait a couple of days or weeks...I'm not so sure.
<< judging from the japanese launch, these will be easy to get at a brick and mortar store: they had 7 or 800,000, and only sold like 300,000 the day of launch. >>