Among older, traditional journalists there is often a palpable sense of newspaper protectionism: lightweight, predictable, and often just plain wrong assumptions about, and rejection of, the digital age, accompanied by a cosy nostalgia about the sticky, sour smell of the presses and the reassuring crumpliness of the papers they delivered as a lad.

It is an inevitable and very natural process of evolution to resist change, which is why it is refreshing to hear those digital realisations from Jon Snow: a man of, well, some experience.

"Citizen journalism won't supplant professional journalism, but it may actually professionalise it," he told the MediaGuardian Changing Media Summit. This openness and transparency may even help to inspire greater public trust in the press.

"There's a sharp, exciting world there - made more exciting, more comprehensive and more vigorous in maintaining democracy by conspiring with the citizens and exposing the unprofessional media, which is what citizen media is doing all over the world."

He said it would be a good thing if half the people working in journalism had left in five years' time.

"I don't have anything against alcoholics, but when I entered journalism frankly there were plenty of people that just shouldn't have been there. Massive media organisations protect these people."

Leather-kilted web genius Ben Hammersley said the best user-generated content on the Guardian's Comment is free site is almost as good as the professional content.

"It's quite obvious if you're a professional journalist that if you're not very good, you're screwed," he said.

"At some point your editor will start saying - why are we paying you this much money when Joe Bloggs the pyjama blogger is writing comment that is better than yours?"

The reticence of some traditional journalists to engage with blogging, he said, could be to avoid highlighting their own shortcomings.

But rather than signalling the 'death of big journalism', citizen media and internet culture - particularly blogging - has fostered a spirit of transparency and whistle-blowing. This is already having a knock-on effect on the traditional practices of both journalism and corporate advertising.

"You can't build a brand around a crappy product any more," said Mr Hammersley, technical mastermind of much of the Guardian's websites and also a blogger.

"If your product is bad it will be outed immediately. It's a kind of Darwinism; if you make bad stuff you're going to die."

Advertising types in the audience reeled; one commented that it seems to be less about bad products and more about convincing bloggers that something is cool.

But, Mr Hammersley argued, the best adverts are shared and distributed between people online.

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