Remember it's not a MTF so tactics are quit important. From what I remember they were quite slow before Andy attacked that year. This year there was pressure on from the beginning and several contenders were shelled out before they got out in the open, so the difference was probably made in the first part of the climb. Still, this was a big performance from Pinot. The northern wind also played a big role (I can't remember how the wind was in '10), but I'm not sure how much of an impact it had in the 'forest' part of the climb.
edit: Only the last ~2.4km are out in the open (where they had a tailwind).
http://i.snag.gy/iYeep.jpg and
http://i.snag.gy/mRYFn.jpg shows this. However it seemed to be very calm before the last 2.4km, so I don't think the wind played a big role there, Movistar's pace did.