The Guardian should not be prosecuted for publishing Snowden's NSA files. They are already available on the Internet, and they can not be deleted now. There would be no point in prosecuting the Guardian as it would just be a waste of time and money. On top of that, they did nothing illegal.
A newspaper's job has always been to report clearly and truthfully. Just because something is supposed to be secret does not mean that it should not be reported. In fact it might be that it was the Guardian's duty to publish this. Snowden is not an enemy but more a teller of truth.
Yes Edward and the Guardian should both be prosecuted for what happened. Granted the NSA may not have been right but what Edward and the Guardian did could be viewed as worse. Even if the public has a right to know the truth they were still breaking a lot of laws.
No, the Guardian should not be prosecuted for publishing Snowden's NSA files, because the government should not be censoring journalists. The journalists are not obligated to align militarily and strategically with the government's wishes. That is the same as government-controlled media. The media should feel free to report to the public as they see fit.
Because the press is generally free, it shouldn't be punished for publishing Snowden's leaks to them. That being said, I feel that the Guardian made a poor judgment call, and what they did could have endangered people's lives. If something more serious had occurred as a result of their story and the leaks, then I do think they should have been punished in some way, and I do believe Snowden himself deserves to be punished.
Although I disagree with the Guardian's decision to publish Snowden's files, the freedom of the press is probably one of the most important in the world and it was their decision to make. Suppression of the free press is one of the things that leads to oppressive governments and should not be tolerated. When the press is restricted in what they publish, it is likely to be followed by restrictions on the individual.
The publishing of the NSA files is a textbook example of a whistler blower case. Given that the US Court system failed to address these privacy issues in other cases and going to the government and asking them to "stop spying" was of no use, the Guardian did the right thing and exposed the world to the level of criminality employed by the NSA. This has led to a fruitful debate on the limits of government powers, heightening citizen awareness and helping bring the government to account.