Since you can buy an iPhone 3G in Europe and have the phone store unlock it for you, that means you can actually unlock the 3G other then using the SIM unlock.

So, can't someone just find out how it's done? Or it has to be a special model which is "unlockable" 3G?

BTW, didn't Apple mentioned something about a special cradle that can unbrick your 3G and is distributed to all of the iPhone 3G selling stores? Does it have something to do with this topic?