I respect your opinions, and I certainly respect the strength of your conviction about WikiLeaks. Most people seem to be taking a white-or-black stance on this, but I'm stuck somewhere in the gray.
Regarding the leaked cables (at least the ones leaked so far), I'm finding it hard to believe that the leak has caused permanent or significant damage of any kind. Diplomats will have to work overtime to smooth some ruffled feathers, but I haven't seen evidence of a shift for the worse in international relations.
If the worst outcome of these leaks is "even greater clamping down of information and ... a new age of the security state", then there is something fundamentally wrong, that goes beyond WikiLeaks. It seems irrational to argue that such changes would never happen IF ONLY WikiLeaks wasn't around.
The closest analogy in terms of effect on American policy and society would be 9/11. 9/11 was a barbaric, indefensible act, but the US has vastly over-reacted in the following decade, with no signs of slowing down. How much of the blame for the over-reaction belongs to Al Qaeda, and how much points to a systemic problem with how the US government deals with crises and the tradeoff between security and personal rights?
Now, WikiLeaks hasn't flown any planes into buildings. They haven't killed anyone. They've made state secrets public, which is a serious matter - but, pragmatically, they've embarrassed and caused more work for a number of diplomats, and not much else. That doesn't necessarily make them praise-worthy, but does it really warrant violent or even lethal opposition?
Look, the reality is none of us have any real clue about what WikiLeaks means. All we know is that technology means the rules are changing. I only really see two possible trends for the future - more openness, or more control. I'm not convinced that what WikiLeaks is doing is right, but given the choice of how I would prefer the world to look like in 20 years, I'd pick more openness over more control. Your preference seems to be for more control, since you seem to feel that an assassination of Julian Assange by the US government would be justified.
Edit: saw your comment about assassination. You can disregard that part of my comment, although since Julian Assange is not a US citizen (and neither am I, for that matter), our ideas for what "lethal force" implies in this context are probably different.
Edit2: Have you read "The World is Flat"? It may seem tangential, but I think it has everything to do with people's perception and expectations of WikiLeaks, and the changes implied by this episode.