Is the publication of diplomatic but apparently unclassified documents illegal?
Has the classification status of these documents been verified?
Is Wiki Leaks the criminal or the persons that obtained the original documents the criminal?
The source of the documents is part of the issue. The documents in question came from a secure network where the presumption is that all information within that system is classified until reviewed and released from classification.
The EEFI is an updated name for what DoD used to call Sensitive But Unclassified. The documents in question appear fall into that category. They still need to be reviewed and declassified before released. They do have fewer controls on storage. However, they do need to be shredded/burned when not needed.
In my understanding of the system, the person removing the controlled documents from the controlled space and providing them to an unauthorized source is guilty of a crime. The level of classification can influence the severity of charges. And, intentional vs unintentional also influence the severity of charges.
Once released (even though improper), there are laws that come into play against publication.
What is interesting is that Bush administration was hammered hard for the release of the name of a CIA operative (considered EEFI) while the current administration is getting a pass on intentional release of more sensitive information and a greater volume of information. I understand that some of the previous WikiLeak info was either confidential or secret.