Although it seems like this is a joke from deep within the bowels of hell, yes ... there really was a version of Diablo being developed by Blizzard (apparently) for the Nintendo Game Boy. It's hard to imagine this hellfire-filled hack and slash RPG on the family-friendly Game Boy (just imagine playing this in church), but Past to Present Online has some screenshots including a picture of the development cartridge, and even a video (which can also be seen after the jump).
It's not terribly impressive, and is no doubt years old, but just imagine what could have been.
