Rumors are floating around that Nintendo is working on a new device, possibly the DS 2, that has larger dual screens and support for higher resolutions.
The new screens can be used as separate displays or as one giant screen, displaying the same content spread across both LCDs.
Its also rumored that it will have a "iPhone or iPod Touch" like tilt motion feature.
The internal guts are supposed to rival GameCube or Wii play making one little powerful handheld.