Today's USA Today (yeah, I read it and prefer it when I'm on the road -- which is pretty much all the time) had an article about the "Gray Market" for electronics her in the USA. Essentially the retailers in the gray market, purchase electronics in other countries where they are cheaper and then re-sell them in the USofA at a lower price than the normal retail products.
Vendors, such as Nikon, don't like this and fight it, primarily by refusing to perform warranty repairs (and some refuse to provide *any* repairs)
I tend to always buy electronics with USA warranties. The prices for the gray market equivalents at reputable vendors don't justify the lack of warranty. Even at one of the most reputable camera dealers, B&H Photo, where they typically price both gray and USA market versions of the same product, I've always picked the USA product.
I find it quite hypocritical that these same companies feel it is their right to shop around the world for cheap labor for their manufacturing while they try to prohibit their consumers from doing the same.
I think it would be interesting if any vendor that used a global labor force had to live by a global pricing model (and therefore, support warranties on even gray market materials).