Like the stuff on wiki leaks has been made available and is now not classified? Because someone published it?
Like the information from Edward Snowden is no longer classified?
Forgive me if I'm not catching your entire point. I'm drawing a distinction here that is part of the security vs. liberty trade-off.
If someone deliberately reveals information that he knows was classified by a duly delegated authority to protect the current safety of the Republic, fry him.
If someone refers publicly to information that might once have been classified, but is now a matter of public record--general knowledge--even if the party who originally revealed it was wrong to do so (and one hopes has been duly fried), you can't go after him for reading it or talking about it now. It's public knowledge. In that sense, he's not saying anything new. Morally speaking, the leak itself should be denounced, but the "leak event" is over.
To take an extreme case, if I today reveal the information that was written on the paper hidden in Major André's boot--long after the trial is over, the fort has been secured, and André sent to his reward--I have committed no crime against our Republic. But at the time leading up to his trial and for the period thereafter, when the fort was still in danger, the information was still classified and in fact known to very few people. The original act of conveying the information to André was indeed a crime, as was André's attempt to deliver the information to the British. But us talking about it now is fine, and in fact it's important for us to know about it and discuss it.