I'd say it's a spoiler just knowing there is a head in a box in Se7en. Maybe a mod could change the title?
EDIT: Darn it Alex, ya beat me by one stinkin' minute!
Not to be a jerk or anything, but I don't kow how you could ask that if you watched it, Doe flat out tells him, paraphrasing "I paid a visit to your pretty little wife..." that and the quick cut (no pun intended) of his wife's picture that they flash.