Nothing in the leaked documents is substantively surprising. We all knew, or should have known, that Arab nations are very nervous about a nuclear Iran, and also very nervous about saying so publicly. We all knew, or should have known, that Russia's democracy is woefully corrupt and that some of its officials are in bed with organized crime. We all knew, or should have known, that some "diplomatic staff," of all nations, are really there to gather intelligence.
We also all knew, or should have known, that diplomats and other people working in government have opinions and make jokes to one another.
It's a great shame that many of these people will now have to be transferred, have their careers interrupted or put along different paths, and that there is a degree of embarrassment particularly but not exclusively about U.S. diplomacy. But it's not like diplomacy is going to stop, either by the U.S. or anyone else. It's not like intelligence gathering is going to stop, either by the U.S. or anyone else. There's more sunshine on the process now.
The likely result of all this is going to be greater use of "top secret" designations for documents that probably don't really need to be treated that way.
Whoever leaked the documents has committed a crime. WikiLeaks itself, however, is a media outlet and does not seem to have committed a crime. I take the claims that peoples' lives are in danger with a grain of salt -- the ones whose lives really are in danger because of the exposure can be moved and protected.
I don't pretend to know whether Sweden is right to pursue a rape indictment against Julian Assange. But that's an entirely separate matter than leaking these documents and as I recall, rumors of that indictment pre-dated anything relating to the diplomatic documents release. If Sweden is, either on its own or bowing to pressure from another nation, going after this prosecution because of the WikiLeaks thing, that's pretty scummy.
Overall, I'm not pleased that the whole thing happened, but the media, the blogosphere, and the pundits are assigning more importance to it than seems warranted.