Following Nintendo's announcement that it's working on a new DS console with 3D support, some rumors were published at various websites. Reports claim the device will have a device about the same size as the original DS, and that it may use Sharp's parallax screens to achieve goggle-less 3D. Other rumors claim the device may have rumble functionality and some sort of "3D stick" control or analogue controller, and that the device will have faster WiFi and improved battery life.
There's been a lot of wild speculation admittedly, but some of the more credible sounding rumours at the moment come from Nikkei and say that the 3DS will boast rumble functionality and some sort of '3D stick' control or analogue controller.
Nikkei also reckons that the screens will be smaller than those used on the DSi XL, which had two 4" screens, and will be about the same size as those on the regular DS models.
Other Japanese media sources are suggesting that the device will use Sharp's parallax screens to achieve goggle-less 3D, basically featuring filters over the screen that cause the right and left eye to see different images. While parallax screens can be used to generate 3D effects one of downsides is that you need to view them from quite specific angles in order to get the desired effect.