I'm just finishing Brian Solis and Deirdre Breakenridges' Putting the Public Back in Public Relations: How Social Media Is Reinventing the Aging Business of PR. 
You will want to read this book. It collated many thoughts I've had about PR and why it has failed in the past and could succeed in the web-enabled future. Our how it might morph into something completely different, and much more effective.
Its co-author, Brian Solis, embodies what he writes about. He blogs about clients, throws parties for them, takes photos of them. He doesn't sit back and send press releases or annoy journalists with email. He becomes the disseminator himself.
that jumped out at me was "The future of PR is already underway and
it's defining who we are and what we choose to represent." BOOO-YAH.
What we choose to represent. Say it over and over. PR people have
choices about what to represent, and more and more they are identified with the communications of their clients, even on the agency side.
Looking at it that way changes everything. It makes the PR person and the "journalist" interchangeable under the best of circumstances. That will be a hard change for some people to swallow.
In the twenty years I owned a PR agency, the thing I hated the most about it was the assumptions people made about me. As a film reviewer (before I opened the agency), everyone thought I was blunt, truthful to a fault, and perhaps even intelligent or insightful. Once I was in PR, all that changed.
Even the journalists and companies that depend on PR to "put out" information disrespect it. For some reason, it is assumed that if someone is "in PR," they will distort the facts and force them own your throat. The worst PR people do that, but the best PR people were never like that. They were and are evangelists for products and companies they know and love, using their communications skills to evangelize. Sometimes they are paid, sometimes not, but if they love a product, they talk about it.
Now PR people will be even more, Brian says. They will find the conversations on the web about products and services they choose to represent, and they will contribute (or not) to those conversations.They will be cultural anthropologists, listeners, analysts of online behavior, and collaborators. More than anything, they will be facilitators of conversations that are already happening about a product and a brand.
That's what I always thought I was. And that's why I think the big agency model is out the door.There's a limit to the scalability of listening, analyzing, and evangelizing.
When you have a big agency, you often take clients you have to struggle to evangelize for within the ethics and constraints of your own personal beliefs. That's how big agencies end up with countries that support terrorists, or even dictators and war criminals as clients. In the new model of social media PR, those clients should gravitate toward agencies that share their beliefs, not just agencies with big connections. When that happens, the industry will have really changed.