Sometimes it feels like hackers do things just to prove that they can rather than for any actual useful purpose. Case in point, Japanese homebrew developer SofiyaCat has set up a minimally-functional DS emulator on a hacked PSP. The compatibility is reportedly spotty and the emulation runs extremely slowly, but you can count on the community to improve these problems in due time.
It might seem pointless to emulate the DS on a system that only has a single, non-touch screen but ... well actually it is pretty pointless. But it is possible, and that's all that matters sometimes.