For all the people who pay attention to physics engines, SSBB has been confirmed on the Havok web site to be using their engine. But what does that mean? Wiki says:
"It is designed for computer and video games by allowing interaction between objects or other characters in real-time. By using dynamical simulation, Havok allows for more lifelike worlds and animation, such as ragdoll physics."
Okay then. If you still aren't getting it, other games that use this engine include Dead Rising, Oblivion, and Half-Life 2. But overall, I will need to see more of the game in motion to say what effect this has on it. Still, kinda neat.