If I could modify slightly my stance that Assange has broken no laws....
First I am not a lawyer, but having read up on the legal implications of the leaks, I am going to venture a prediction that Assange will be charged under several US Acts/legal thingies. It is actually quite hard to find independent legal discussion on the subject as it seems every 'expert' holds a personal view. 'He did a bad thing and should be charged' or 'he is a hero the laws don't apply'. These from legal professors and ex-prosecutors, etc.
But one guy was saying that it hardly matters as US prosecutors often press charges on dicey grounds, if for no other reason than to seek clarification. Obviously the Espionage Act is weak and outdated, but as they see a hole in the system they will seek to use Assange as a way to find out its limits, and then they can better plug the hole. So Assange is charged, extradited, the lower Court knowing it is a big issue finds him guilty knowing it will be appealed to SCOTUS. SOTUS to my knowledge hasn't issued a strong opinion on the matter - the Pentagon papers case was not actually fully resolved.
Critical questions, in my opinion, relate to whether a website (Assange) is a journalistic endeavor, whether the First Amendment applies and whether the Act can be applied to foreign nationals operating outside the country. If prosecutors include charges relating to stolen property they will run into other challenges such as the fact that government documents are not copywritten (copyrighted?). Before any of this can take place there will be a quite difficult extradition process, as there are obvious political elements involved.
Just thoughts...