Well, now we have two different stories...
1) Anakin loses his arm, from above the elbow, in the Hangar Duel.
2) New report from T-Bone's Cinescape:
Yes, it's true. Anakin loses a hand in EPISODE II's duel. I'm pretty sure it's the same one that Luke cuts off in RETURN OF THE JEDI too...the right hand.
Now, the thing that's pretty cool is this: He's not given a new hand right away ala Luke at the end of THE EMPIRE STRIKES BACK. He's given this mechanical looking cybernetic hand that is VERY SIMILAR to C-3PO's before he has his coverings, but there are no metal platings around anything but the fingertips which are shaped like real (metal) fingertips. It's all just metal framing and multi-colored wires.
Did Lucas feel that the entire arm was overkill? Was there some aspect of filming originally that caused this change to be made? Or was there no arm-cutting to begin with?
This is one major spoiler that has only really been hinted at. I actually like this new report. It's more eerie, like looking under the black suit....