The scene is revelaed below, but beware...MAJOR SPOILERS ARE AHEAD!
So you heard that Anakin loses a leg? I'm impressed, they haven't even shot that scene yet - maybe this week? Between that and his arm and you've got a wicked mixture of man and machine. That, and that whole burned to a crisp deal. Literally.
Well, I've got something else to add. His leg is gone from about the knee down or so, not at the thigh like some have speculated. AND he loses something else as well. All of his hair is gone - singed in the fire. And he gets that massive head wound in Episode III - the one you see briefly on Vader unmasked in Return of the Jedi.