Difference between the US and Japanese versions of the Nikon D90?

Why the significant price difference?

Japan has this habit of keeping superior quality products for local consumption and exports items that have passed through lesser quality control standards. You can only buy the Japanese version in Japan at local stores with the help of a "native". If you shop at the much larger stores in Japan where foreigners usually troop to, they will give you their "for export" cameras at a heftier price.

Talk about nationalism. That's the right way to do it, in my terms.

So George tell me, how would Nikon know if a camera was purchased off the gray market? Canon doesn't. What if you'd bought the camera 2nd hand, how would you or they know it came from the gray market and are you saying they wouldn't fix one if you took it in for repair? My Kiss3 is marketed as the 500D in some countries and the T1i in America. Don't know why that is because my 5DM2 has the same name everywhere. I selected the Kiss 3 from Japan because it was $50 cheaper than the T1i. Its the same camera. I purchase all my camera gear off the gray market. I have to. There's only one authorized Canon dealer in the country I live in and because of high import taxes it can't compete with the gray marketeers. I'm not talking about little shops down back alleys waiting for some unsuspecting tourist to wander in. I'm talking about huge businesses that are growing bigger by the day. You don't grow by giving your customers shonky warranties that can't be honored.

The Japanese versions and the US versions are exactly the same cameras. The only difference is that the US ones are imported by the Authorized Nikon dealers and because of that, Nikon USA will support you. If you need a repair, in or out of warranty, Nikon USA won't repair a "grey market" Nikon product, even if you offer to pay for it.

What you are paying for is the support of an officially imported product.
http://support.nikonusa.com/...-market%3F
http://www.bythom.com/warranty.htm

Addendum to "ooo":
Nikon looks that the unique serial number of the Nikon product before providing service. Just ask any camera service center and they'll tell you the same. If you've bought the lens or camera body from someone else, they don't care. It's all in the serial number that identifies who imported it.