There was a trick in one of Penn & Teller's books where they made use of an instant camera. They'd have an audience member think of a vegetable, they'd take their picture and when it developed the vegetable they thought of was in the picture with them.

My question is this: will the recent slate of instant cameras lend themselves to this effect? Or was this something that could be done with the older instant cameras like the one-step?

I think there are apps that can do this now.