The demo is a castle make of bricks and big blocks and you can destroy it with cannon. The castle has 5,000 blocks and each one can interact with each other. This is very expensive as it takes a lot of calculations. Intel doesn't use Ageia - it uses some other proprietary physics engine. The more objects you have on the scene, the less performance you have from the real physical objects. If you use 10,000 blocks the performance becomes tragic.
All of the next gen consoles and computer are multi core, so you have to think multi threading. More and more games will have to start using multi threaded code. Soon after dual core, we are in the dawn of quad core and we will get even more cores down the road. But it is not easy to do multitasking and Intel proved that ages ago with hyperthreading. µ