Whoever it was, he or she is obviously playing with fire and the WikiLeaks founder himself may be charged with espionage; Julian Assange is also investigated for rape in Sweden. More generally, it has both advantages and disadvantages to "measure" the intermediate stages of various processes. Note that in quantum mechanics, much like in diplomacy, such a measurement may influence the final results.
Obviously, the influence may be both "positive" as well as "negative", depending on whether the "secret work" is more constructive than the opinions of the interceptors who may interrupt it in the middle - which may include the whole public.
To get the honest quantum mechanical results for the original question, you must sum over all conceivable histories. It is often better for sensitive processes, research, and negotiations not to be interrupted and distracted in the middle.
However, once the diplomatic cables are published, I don't think that they're excessively shocking. We have still learned something, namely that
- behind the scenes, the U.S. administration has a somewhat tougher attitude to Iran than what we can see publicly; however, this attitude could still be included in the impotence category; Gates himself believes that an attack on Iran is hopeless without the U.S. and solves nothing even with the U.S.
- Israel is doing and thinking exactly what we publicly see; as far as the leaked documents go, the Jewish State may be described as the most honest country in the world
- Arab countries urge America to bomb Iran; they're clearly more afraid of their Muslim comrades than what they're ready to openly reveal
- Russia is also afraid of Iran and the big Slavic country is actually excited about the missile defense technology; it may be more excited than many Americans; Russia may try to build its own systems and/or shared systems with the U.S. or others
- Brazil didn't want to join war on terror
- China has abandoned the North Korean comrades; it's clear that China no longer considers the totalitarian "spoiled child" (Chinese term) a useful ally and it won't protest against the incorporation of North Korea into South Korea once the commies collapse - either spontaneously or in a stimulated way (e.g. by Japan, as the papers indicate); this is probably going to become the official policy, in fact
- the Czech Republic is working hard to strengthen the U.S. influence within the EU; that includes some help with the steps against the Iranian nuclear program; some people in Czechia find this finding surprising but I don't find it surprising at all; in fact, the trans-Atlantic link seems to be an official value promoted by the Czech foreign policy
- prince Charles is not in the same league as the Queen when it comes to his natural authority in the Commonwealth
- Berlusconi gives wild parties; Merkel is made out of teflon; Putin is an alpha male; the U.S. worries that the Argentine female president doesn't take enough psychiatric medication; Hamid Karzai's brother is probably corrupt and a drug dealer; Mugabe is a "crazy old man" (not only) in South Africa; Gaddafi was intimately close to a voluptuous Ukrainian nurse