Ahead of retail, Sega already has a presence on the PSP Vita. According to an article from Engadget, the just-released-in-Japan PSP Vita has already been modded to play Sega Genesis games. Or, to be exact, has been modded to run an emulated PSP emulator to emulate Sega Genesis games. That sound you just heard? That was your mind doing yoga around that sentence.
The proof is in the pudding which is after the jump.
Anyway, appropriately enough Sonic and Knuckles was chosen to demonstrate this functionality. Assuming Sony does not release firmware blocking this functionality (never happens, right?) it looks like PSP Vita, like the original PSP before it, will be another choice for emulated retro on the go. If they can get the sound right.