I found this pretty disturbing, to be honest. It appears Luigi's shadow hung himself in the telephone room. To activate this easter egg, go to the telephone room during the blackout and answer the ringing phone. When the lightning strikes, look at his shadow. CREEPY. It's really just Luigi on the phone. Spoiler alert.

http://www.youtube.com/watch?v=kjejTiRoOgk

Also, Here's the beta video of Luigi's Mansion(WARNING: If you get scared easily, then don't start watching this video):

http://www.youtube.com/watch?v=2FK761NSLn8

I think the beta game-over screen was rather scary. I'm glad Nintendo changed the beta game-over screen of Luigi as a zombie to the title screen.

We've got a thread for this sort of thing here if you'd like to discuss this there, Jaybuscus. Thank you! :3