Years ago, Nintendo released the Nintendo DS and the DS Lite. Anyone could import them and play games on them. Those days are long gone, and with the Nintendo 3DS, they don't look like they're returning.
According to an email from Nintendo's Japanese support, the Nintendo 3DS is region coded, which means that players cannot play games from different regions on the system. As Nintendo support explains, if one plays a Korean 3DS game on a Japanese 3DS (or vice versa), it won't work — and so on and so forth.
This should come as too much of a shock as the Nintendo DSi and the DSi XL have region codes.
Kotaku is following up with Nintendo to confirm whether or not the 3DS is actually region locked.