It's rumored that Nvidia has won a contract to supply Nintendo with Tegra chips for the next generation DS. The specific chip Nintendo plans on using is unknown, so we don't know exactly how powerful the next model could be. Considering the current DS runs on two incredibly slow processors, any Tegra would be a huge boost in power.
As a bonus, the source reports that the new hardware should allow backwards compatibility. Hopefully not à la PSP Go, where backwards compatibility really means you have to buy all the games you already own again. [Bright Side of the News via Electronista]