Hello,
i have a white iphone 3g with the latest FW, Bootloader and Baseband. This is a locked iPhone, i dont know from which location. So no yellowsn0w. I think it's AT&T. Now i use a turbosim adapter with a German "Base" Carrier and internet flat.
BTW: is here some place to write a review about this?

My question is: There are unlocked iPhones in the world, why isn't it possible to copy this firmware from these phones? Or why couldn't anybody enable the real unlocker.

Please, use the search tool. Your question has been answered in other threads.