Having heard from "credible sources from within the mobile graphics industry", Digital Foundry have done a little digging and come up with probable hardware guesstimates for Nintendo's alleged next generation of handheld hardware.
They reckon that, with the rumoured machine due to launch late next year, it's going to be powered by the second iteration of nVidia's Tegra chipset, not the original as was first suggested. For reference, the Zune HD - capable of stuff like this - runs on the Tegra, while Nintendo's new handheld would be running on the Tegra 2.
nVidia reckon the Tegra 2 has four times the power of the Tegra. So look at what the Zune HD can do then imagine something... better.
Course, we still have no idea what Nintendo have planned for their next handheld; it could be another two-screen device, it could be a return to the single-screen days of the Game Boy, it could be something else entirely. But hey, whatever it is, it's nice to know (if this info checks out) that we're looking at a substantial upgrade from the current DS tech.
Oh, and if you're interested, the Digital Foundry piece also has some less concrete stuff on Sony's supposed PSP2 as well.
In Theory: Nintendo DS2 vs. Sony PSP2 [Digital Foundry]