Don't trust your printer! There were a lot of demos of printer hacks at 28c3 and basically I think I might not print anything ever again. A lot of these things have their firmware implemented in postscript. Updating the firmware consists of printing a special document. It's pretty mental tbh. Your jaw will be scraping along the floor at some of the holes these things have.

Print Me If You Dare: http://www.youtube.com/watch?v=njVv7J2azY8

Hacking MFPs: http://www.youtube.com/watch?v=PqL5P46m_zQ

EDIT: Beaten by 4 hours. Oh well.