So far Nintendo is remaining mum on the subject of how they did it with the 3DS. So let's post speculation here about it, until they finally tell us.

EDIT: I've been informed Sharp makes the screen, so please ignore the misinformation in the title.

My friend did some research, and the 3DS looks and works sort of like a hologram card. Its not as 3D as the expensive TVs or in the cinemas, but its good enough to be revolutionary

you mean Sharp ? sharp did the tech not Nintendo.

There're some threads on that matter, specifically concerning Shard 3D displays and tech behind it. Is that what you mean?

//BTW what's up with forum search? Can't find anything.

I assumed it has has 2 screens, the real screen and a very thin layer of 3D glasses type material on top

I thought it was funny during the Nintendo conference Reggie mentioned that 3D was big as CES but he also mentioned that usually for 3D you need glasses.

But AT CES this year there were TONS of technologies that can produce 3D without glasses.Intel and Samsung also have something in the works. I used to have a link to a youtube video that explained each of them but I can't seem to find it right now.

I've heard it uses autosteroscopic imaging to get a 3D effect.

http://loot-ninja.com/2010/06/22/how-the-nintendo-3ds-screen-works/

This seems the most plausible method, as those who had hands-on time with the 3DS said it had a margin of error on it.

That actually sounds really logical. Why haven't the TV manufacturers simply placed a second screen (Glasses) over the origional screen to give all viewers the 3D effect without the glasses. May make the TV alittle more expensive but it would save people the cost and embarrasment of wearing and buying additional glasses!

Anybody know why no one does this?

People already bought 3D Tv so their up for a huge disappointment.

Anyways, i believe Nintendo is doing it using the front facing camera and using Sharp's Parallax barrier screens which can send two of the same images to each eye so that the brain can interpret depth.

http://www.youtube.com/watch?v=lAS55_RngoQ

I don't know if it is the same tech, but it already well known... I guess