Included with every 3DS sold will be six cards. They may look like plain paper cards, but they're actually "augmented reality" devices, which when detected by the 3DS' camera come to life on the handheld's top screen.
We've shown you what the question block card looks like, but that's just one card. There are five more that come with the 3DS, and those other five are way cooler.
You can see them up top, how there's one each for some of Nintendo's most revered characters, like Link, Mario, Kirby, Samus and...some Pikmin.
If you play a certain Augmented Reality (AR) game (there are six included with the 3DS), these cards will bring those characters to life. So instead of the dragon you can see in this clip here, you'd be seeing a little Mario, Samus or Link pop up on your desk / coffee table / lap.
There's no real game to go with them, but that's OK. I'm happy enough having little Link just stand there, keeping me company with his cute little hat while I toil away.