that's a pretty easy affect to get in PS. just make the shape you want, in the case you posted above, it looks (to me at least) like mickey mouse....sorta...in anycase, once you have that layer, you take your face layer and place it directly ABOVE the shape layer. then, in the layers menu, you hold down option/alt, and mouse over the line dividing the layers. this will create a layer mask, and will place the face right inside your shape. After that, you can move the face around as you want, affect it's opacity, give it a blending mode....er whatever you want to do to make it look spiffy.
Edit: Also, this technique is considered Non-Destructive...which means if you change your mind later, you don't have to worry about having merged layers, and you can simply take it out of the mask.
Last edited by Feller; 08-17-2007 at 04:25 PM..
Reason: one more thing...