From the time I first heard it, the acronym PR has always had two different meanings to me. PR could stand for Public Relations or it could stand for Press Release. In what the Cluetrain Manifesto called The Long Silence (a.k.a. the days of the Mad Men), these two meanings weren't all that indistinguishable. In today's Wikinomics world, ruled by the prosumer generation, these two meanings are as different as night is to day.
In the old days, a PR group was all about selling media. How much broadcast time on radio and TV and column inches in magazine and newspaper print could you afford in order to condition your prospective clients to chose your offerings? That is still necessary but no longer sufficient in today's world. Now, a PR group has to also be concerned with establishing authentic conversations. Can your community managers effectively attract and keep people interested in interacting with each other around your offerings? Can you establish and maintain buzz? If you can't, then it will be quite a long time before that cat barks.
Your marketing message in the broadcast only world had to be broad and appeal to a wider audience. That won't fly with the prosumers. In addition to your broad message, you also have to develop lots of narrowly focused messages to appeal to a wide array of niche markets. Remember, they are no longer passively taking in your message. They now get to talk about your message with everyone else. So, give them something that they are interested in talking about. How do you create these narrow messages without becoming self conflicting? How do you do all of this on a tighter budget?
No wonder it's so hard to find a good PR group these days.