MotionX has released a free app called MotionX Dice [App Store]. The free dice application provides you with five dice that can be rolled by simply shaking your iPhone. The physics and visualizations serve as the basis for their $4.99 game MotionX Poker [App Store].
The $4.99 Poker game uses the same dice-rolling technology. By also adding betting structure and the ability to unlock higher tables and dice, MotionX has done an excellent job in creating an enjoyable gaming experience. (Full review).
For those who have little interest in Dice poker, however, this free Dice app is a must download just to experience their dice-rolling simulation.