The multitouch UI is great but can be a little awkward when it comes to "pinching" in order to zoom or expand the screen view. This may be obvious, but there is what I find to be a more stable and less awkward alternative. Instead of pinching, place the thumb on the hand you are holding the iPhone with anywhere on the screen. Then just use the index finger on your other hand to either magnify or expand the view of whatever is on the screen. I usually hold the iPhone with my left hand so when I do this I just place my left thumb on the bottom left corner of the iPhone and then use my right index finger to do the zooming by sliding it diagonally across the screen either towards or away from my thumb.