With due respect for Tom Murphy, the internet really has changed everything. Just as the Gutenberg press changed the world, that is how profoundly the Internet is changing our world.
The Gutenberg press gave the world a cheap means of reproducing print. Thus who could distribute material and what they could distribute was greatly increased; but they still had the costs of the press and the costs of distribution.
The Internet solved the problem of distribution, but you still had technical barriers to entry, you had to know HTML, or have enough money to pay someone who did, and you had to pay for hosting. Blogging removed even those barriers, now anyone with a modem and an opinion is a press lord. Indeed, with YouTube, anyone with a digital camera a modem is a video lord. This is a very different world.
Organizations have to communicate with, and respond to, a far more diffuse group of influencers. We have more opportunities, but many more challenges. In a world of social software, who is a source? who is a journalist? who is a newsmaker? The roles are blurred. The whole phenomenon of blogswarms, the differences between the various social tagging sites, all this must be carefully studied. We still have the old reliable 250 word ASCII text email press release; but we also have a vast new world we must respond to.