I don't think it's particularly helpful to think of the conduct of international diplomacy in the same terms as interpersonal relationships. Diplomacy is and always has been a hardheaded game of Realpolitik played by unsentimental professionals who are expected to be ruthless, though whenever possible politely ruthless, in the pursuit of "the national interest", however that may be defined by the government of the day. The US (and other countries) routinely post spies overseas under diplomatic cover, which I think says a great deal about how anxious they are to preserve the myth that diplomacy is a pristine gentlemens' game unsullied by deceit or subterfuge. For this reason I doubt there is much in the Wikileaks document dump that is really going to shock the sensibilities of the world's chanceries. No doubt in many cases they already knew or at least suspected what the documents confirm.
Speaking more generally, I think Wikileaks is providing an invaluable public service. A "democracy" in which the people are kept in almost complete ignorance about what their government is doing in their name, so that they are unable to make informed decisions about public policy or hold public officials accountable, is a democracy in crisis. Power resides not with "the people" but with officials, both elected and unelected (but probably more with the latter), who use secrecy to give themselves the maximum freedom of action while very carefully controlling the release of selected information, often false, with the connivance of a craven media establishment to manipulate public opinion to support those actions (in a technical sense this is called "propaganda", but no one dares use that word in relation to the US government. It requires an intellectual leap most people are as yet too timid to make). The US government concealed or told outright lies, and not once or twice but a great many times as part of a deliberate and ongoing program of public disinformation, about Iraqi WMDs and ties to Al Quaeda, about Jessica Lynch and Pat Tillman, about its policy of "extraordinary rendition", torture, and extrajudicial murder, about its massive subversion of the civil rights of American citizens, and about a great many other things besides. Lying to the people is now its modus operandi, except when the truth is too inconsequential to be worth distorting.
What I don't get is that many people seem to think Wikileaks is the problem, when it is merely a response to the massive abuse of secrecy that imperils American democracy. If Uncle Sam's obsession with "controlling the message" didn't require it classify all but the most benign and uncontroversial of its activities then there would be no need for the truth to reach the public through leaks. Given that it does however then the only remedy is for those who want to preserve democracy as more than a dead letter to take extraordinary, risky and even illegal actions to put the truth before the public and allow the people to draw their own conclusions, for we are now at the point where the defence of democracy demands no less.
