Nintendo's president Satoru Iwata was more mouthy than most presidents are about their upcoming - but unannounced - products, and said that the upcoming DS will have an accelerometer. Or, some kind of motion sensor.
Here's the quote:
[It will have]highly detailed graphics, and it will be necessary to have a sensor with the ability to read the movements of people playing.
The highly detailed graphics part is a given, but even so, is still pretty vague. It does mesh with the Nvidia Tegra rumours we heard back in October. The people's movements part is a bit more interesting. Maybe some kind of accelerometer for tilt-based gaming (like in smartphones now) could be interesting, but unobtrusive enough for it to still be a DS. [Kotaku]