I've been talking with some friends of mine, and we've come up with a few predictions of what'll happen in Episode III. Please share your own!
Anikin fights Count Dooku, Palpatine's apprentice, one-on-one while Palpatine watches. By this time, Anikin would be more than a match for Dooku, cutting off his arm. "Your hate has made you powerful. Now, kill Dooku, and take his place at MY side!" Palpatine would say. Anikin might hesitate for a second, before slicing Dooku's head off, instead of throwing down his lightsaber like Luke did.
That'd be sweet.
Also, one of the many lightsaber battles will take place in a hostile enviroment. Somehow, this hostile enviroment will temporarily deactivate both jedi's lightsabers a few minutes into the fight. The fight will continue by means of martial arts and the force. Jumping off walls, shooting lightning, and dodging thrown debris ala the Matrix. After a while, their lightsabers work again, and the fight finishes in a spectacular clash.
THE most awesome battle ever!