(Sorry, I’m going to dupe my comments from somewhere not too far from here, because I grow fatigued...)
I think gestures to the extent described in Apple’s gesture dictionary are pointless. The purpose of having multiple touch points is to escape unnatural gestures!
With multitouch (of the theoretically infinite touch points variety), resizing an image does not need a stinking arbitrary gesture. It can track your touching the image and apply some simple math to resize it, rotate it, etc. as you move your fingers.
For example: One corner is being dragged, so the others will follow with it because the material is rigid enough. Two corners are being dragged in opposite directions, the material rotates AND expands such that those two corners are where you put them.
Elegant, tidy and natural. No gestures, just common sense!
I think creating a gesture-driven interface around this technology is backwards. Gestures are not a natural interface; they are a primitive compromise to provide quick control in limited interfaces like single-touch screens or keyboards & mice. That is not what this technology is about.