For those curious on how it works, there are some missions where a police car has weapons in the trunk ("Death From Above" side mission, for example). The piano gun will be selectable. Unlike the image sent with the e-mail, it looks like a Tommy Gun, not a pistol or player piano.
Gamestop just sent me an e-mail and code for a free piano gun for L.A. Noire
. I'm pretty excited to play this game as I'm a fan of solving mysteries and murders in my free time.
Related Link: L.A. Noire