the NDS and DC ones are not playable... far too slow, those are just a (useless) POC , but what's the interest of just porting existing emus just to show they can "run" on a PSP ?
nothing: any kind of emulators written in C/C++ and using sofware renderer can be ported to any console, it's just that this can also run verrrrry slow
I bet those "ports" would also run too slow on the wii, before you ask
the N64 one, on the contrary, is a huge optimized version of daedalus, completely rewritten to use PSP hardware for rendering
just wait for Wii64, it will probably run even better
The N64 emu can only play a few games, and it is far from perfect. The DS emu is super slow, and I doubt it would be worth using w/o the touch screen support. And there is no DC emu yet, nor will there probably ever be.