Ali Fischer's Music for the Jilted Generation is the reason I got interested in public diplomacy. In it, he makes a great case for the collective action of "bazaar" PD while pointing out the flaws of more traditional, hierarchical models.
Ultimately, he argues, the goal of public diplomacy should not be to persuade somebody to agree with you, but rather to achieve shared goals together, or to convince others to work towards your goals by helping them work towards theirs.
It's not applicable to every situation, of course. Nobody's going to argue that the best way for the U.S. to promote democratization in Iran is to help Iran achieve their goal of becoming a nuclear state. Well, nobody outside of Ahmadinejad's entourage, that is. But I think identifying common ground and compromises is the essence of all diplomacy--public, traditional or otherwise.
Fischer argues for an adaptive, engaging form of diplomacy that emphasizes partnership, both online and on the street, and while I may not believe that setting up a SecondLife embassy is the best way to win hearts and minds, I do think there are valid reasons to both widen the circle of engagement and adapt information and communication technology to diplomatic purposes.
Daryl Copeland's paper made less of an impression on me. His argument that diplomats should be "globalization managers" struck me as too broad and vague to be truly practical. There are so many arguments about what globalization means, and what it means to different audiences, for that term to have significant applications. Nor do I believe that the first duty of diplomacy is to manage discontinuity. The first duty of diplomacy is diplomacy. By all means, conduct diplomacy within the context of globalization. Indeed, it would be almost impossible to do otherwise, but be clear about what that means.
Copeland gets around to the point eventually: build relationships and promote development and security -- but how are these goals different from the goals of traditional diplomacy? And his argument that diplomats should innovate and adapt the theory and practice of transformational PD is once again vague.
In my opinion, the best way to promote transformational diplomacy would be to increase collaborative engagement. Social media would be helpful for this, but I think traditional methods of collaboration and interaction are even more important. Exploit the "last three feet" and create meaningful relationships and partnerships to create a base for cooperation and information exchange.
There's nothing particularly radical about the suggestion. Which is probably why PD practitioners have been making it for decades.