In all seriousness these are some huge SPOILERS
Now whether you choose to believe me is your own free will. But I tell you by everything I hold holy, I do not lie. Theforce.net had a spoiler report, a huge one, that was up in the morning I would say about a week ago. Sadly, I was unable to save it not *knowing* they would take it down. It talked about the planet Obi-Wan would be on, Utapa(or Upata, not sure) I think was how it was spelled, and that he would fight General Grevious. What was supposed to be just an encounter between the two to possibly end a good part of the Clone Wars I presume, was more important. They said it had an important effect on the story. And the biggest one of all. Yoda and Darth Sidious will fight each other. Sidious has a red lightsaber and I am betting, though the report didn't say this, that perhaps this "awesome display of darkside power" that Sidious will show in the movie might be in part here.
On a sidenote, for those fans that feel there is too little character development in the prequals, in one of my Star Wars Insiders and I think the Just the Facts section of theforce.net they have a quote attributed to Rick that says we will learn a bit more about Sidious/Palptine/Emperor's origins. The sidenote was not part of the big spoiler I told you that preceded this. May the Force be with You.
Edit: Fixed a few spelling errors.