Remember the Pentagon Papers? The NEW YORK TIMES successfully pleaded First Amendment after publishing them. I think they were right. Except for things dealing with nuclear weapons, we don't have anything like the British Official Secrets Act in this country. The guy who turned the Papers over to the TIMES was the one who should have been punished, but the Administration botched the prosecution.
In the case of Wikileaks, I think First Amendment also applies. The guy who should be punished is that twerp Manning, to violated his oath of office by giving the messages to Asange. He should be executed.