Why isn't Robert Novak in prison?

Ok, I confess. I've not really followed this whole controversy surrounding the possible outing of a CIA operative by allegedly someone in the White House, mostly because it's not horribly interesting.
However, I got a little more interested today, not sure why exactly. I know that Judith Miller went to jail to protect her source, and while I respect the principle that she stood for, I disagree with the concept. Journalists should be required to reveal their sources in situations where national security or the personal security of an individual is at risk. This is the case here where Valerie Plame was supposedly outed as a CIA agent.
The interesting thing here is that the person who originally came out with the story, Robert Novak, has not been put in jail for not revealing his source. Why has he not been subpoenaed? Again, maybe I missed something, but I know that he's not been in jail, as I keep seeing him on TV (lord I hate CNN, but it's all they show in airports). I like Novak, but if he's the guy who knows the source of this entire controversy, why doesn't the prosecutor just subpoena him, get him to tell the source or put him in jail, and we can be done with it?
Well, after getting up to speed on the controversy, I'm thinking that I know why. If we did that, we'd get the guilty party, and the controversy would be over. No more grand jury rumors about Dick Cheney. No more grand jury rumors about Karl Rove. No more distractions, no more news coverage of this ignorance. That can't happen. The people driving this controversy don't want the truth, they just want as much distraction and weakening of the current administration as they can possibly cause, and so far, that's working for them.
The amusing thing is that many liberal-leaning columnists are talking about how they have higher ethics than Novak, because they were contacted by the same sources with the same information, but they didn't publish it because of their concerns regarding security. Funny, they didn't give a rats ass about security when they published pictures from Abu Ghraib, or troop movements.
Overall, this certainly seems to be a manufactured controversy, mostly because Valerie Plame hasn't been a field operative for over two years, and in fact has been working in the CIA offices in Virginia for some time. If people can't figure out that she's CIA by following her to work, then they're dumber than I give them credit for.