The Gospel Truth - New York Times

It's always made sense to me that Judas was acting on Jesus' orders. Jesus was not so stupid as not to know that Judas would eventually 'betray' him. If he knew it would happen the only reason he would keep Judas in his inner circle would be because he knew that Judas would do the right thing, which was, after Jesus' act of aggression in the temple and heresy in the streets, to turn him in to the proper authorities and let the law run it's course. He also knew that the government with which he was dealing was so corrupt that justice would not prevail, and he would be made an example. That doesn't mean he wanted to go through what he did, but he was certainly willing to, thus the, "Let this cup pass from me... but not my will, but thine be done," prayer.

The Gospel Truth - New York Times