I just now noticed that Tegra DOES indeed build itself off ARM technology. I wasn't aware of that at all, so you can sort of disregard what i said. I had no idea that it was sort of in the same family. That changes some stuff I would think. According to wikipedia (which you can choose not to believe of course), Tegra is a mashup of an ARM processor, a GPU, and several memory controllers. So it's kind of like an ultra CPU for portables that can do almost everything. And assuming it IS indeed based on the ARM architecture, it might be feasible to run DS games on it. After all, games intended to be run on a pentium 1 processor can still be made to run on recent hardware. I can easily install an old version of windows on a new PC to get all those old games to run fine. Same might work with DS games. We'll see. Though i still doubt Tegra could emulate the regular DS/DSi. And it's not something Nintendo would be likely to do. If anything, it will be more akin to compatibility mode for Wii that lets you run Gamecube games.
So yeah, consider my before comments disregarded. We'll see what happens. Still really no confirmation on anything about the hardware yet. Too early to jump to conclusions.