I know everyone's going to call me nuts for this, but I was just thinking about Jango, Boba, and Mace.
Rumors for Episode 2 show that Jango will be decapitated by Mace. In an interview Samuel said he will return for Ep. 3 but like all Jedi, he's going to die. This is where I think I'm nuts.
Maybe Boba kills Mace out of revenge for Jango. Perhaps Boba helps Anakin kill the Jedi and that's how they knew each other in "Empire". I know Boba is a little boy, but it is a shocking possibility.
Of course, that's my theory.