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 rumors 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 unintrusive enough for it to still be a DS. [Kotaku]