If you’ve got a version 1.0 Japanese PSP—the kind that will allow you to run unsigned code from your MemoryStick—then count yourself lucky, as the first GameBoy emulator has just shown up for the device and you’re the only ones who can run it. It’s a shame, really, because as much as I love my PSP, being able to play GameBoy and SNES games on it might make the perfect entertainment device. This version looks a little unfinished (not that I’ve run it, but I’m just looking at the non-scaling screenshot), but it’s a harbinger of copyright violation (and, yes, homebrew) to come.
GameBoy for PSP [PSP411/PSPHacker]