Oh, as for the person that was saying it's not James Earl Jones, it is. He's just saying "master" with more of an emphasis on the "r," unlike before.
OT - "mastah" (the "er" is more of an open sound)
Trailer - "mastur" (the "er" goes straight to the "r" sound)
I have said since the beginning, if Lucas screws Episode III up, he's lost forever. This trailer definitely gives me hope that there's still something there and he's been holding out on us.