There's an early piece of poster art that's appeared online for Saw IV, and while it might well be fan art, it does follow the ideas of the Saw posters very well.

Personally I think it is fan art as the poster is far too specific compared to the others in the series. The clues in the poster were always very, very loose and didn't point so closely to a character as this does. However it is really good and very unnerving, and that's what these posters should be.

This Saw IV poster shows Jigsaw's head in a weighing machine. Lovely. You can see the photo over at Bloody Disgusting. It's pretty damn good isn't it?