Thanks to CRAZ1ah for the tip-off. Nintendo's new handheld will also have two screens like the DS and DSi, but both screens are now 3D, without the need for the use of 3D glasses. How this will be achieved, I don't know, but hopefully we'll be getting better graphics and the works.
3DS will be backwards-compatible with all DS games and will probably be released early in 2011.
Source: http://kotaku.com/5499697/nintendo-announces-new-hardware-the-nintendo-3ds
