It's an unusual event: an open letter to the Prime Minister signed by the editor or editor-in-chief of almost every significant mainstream news medium in the nation - radio, television and newspapers - with the sole exception, interestingly, of The Australian's Chris Mitchell.

Its essential point is that WikiLeaks 'is part of the media and deserves our support'; that prosecuting it or its editor, Julian Assange, because WikiLeaks has published confidential government documents would be unprecedented in the United States, and in Australia, 'would seriously curtail Australian media organisations reporting on subjects the Government decides are against its interests'.

In other words, the Walkley Foundation's letter is an elaboration of the attack made in his acceptance speech last Thursday night by Gold Walkley winner Laurie Oakes on the Government's reaction to WikiLeaks.

All very admirable. And I want to make it clear, for what it's worth, that I agree with the letter's arguments as, he tells me, does Chris Mitchell.

But there are a few other points that bear repeating, lest the media get too carried away with the notion that by publishing the WikiLeaks cables it is exclusively serving 'the public interest'.

First, nobody seems to be defending the alleged leaker of this unprecedented trove of secret documents, Private First Class Bradley Manning of the US Army. It seems generally agreed that Private Manning is facing up to 50 years in prison for his indiscretion. Yet despite all the talk about whistleblowers, shield laws and the media's duty to let daylight into the processes of government, no-one is claiming, seriously, that Manning's actions could be justified under the law of the United States or almost anywhere else.

If the allegations against him are proven, Private Manning will be revealed as a leaker, not a whistleblower. With some notable exceptions (Hillary Clinton's requirement that her diplomats spy on the UN, for example) the vast mass of these documents do not reveal wrongdoing, corruption or malfeasance, but the normal activities of diplomats, reporting frankly under the understandable assumption that their reports would remain confidential.

Yes, of course their publication causes intense embarrassment, to the US State Department and to many of the subjects of the cables. Whether that embarrassment, and the effect it will have on the ability of diplomats everywhere (and anyone else who relies on the confidentiality of electronic communication) to report frankly to their superiors or colleagues, is 'in the public interest', is very much an open question.

Second, Private Manning went to WikiLeaks, presumably, because he felt that his identity would be better protected by that organisation than by any other. That may be the case. It does not seem to be through any action or negligence on WikiLeaks's part, but through his own indiscretions, that Bradley Manning came to the attention of the US authorities. However, one reason why neither Julian Assange, nor WikiLeaks, nor any of the great newspapers which are its collaborators in the document release, have been under any pressure to reveal their source, is that the US government has convinced itself (rightly or wrongly) that the source is already known and in custody.

That being the case, the entire justification for WikiLeaks's existence - its ability to protect its sources through its unique information-laundering and encryption techniques - is irrelevant in this instance.

Third, Julian Assange has made another claim for WikiLeaks, which he says sets it apart from other media organisations. According to this op-ed in The Australian last week:

WikiLeaks coined a new type of journalism: scientific journalism. We work with other media outlets to bring people the news, but also to prove it is true. Scientific journalism allows you to read a news story, then to click online to see the original document it is based on. That way you can judge for yourself: Is the story true? Did the journalist report it accurately?

Well, WikiLeaks clearly doesn't insist on 'scientific journalism' being practised by all the media outlets with which it's working. The Age and the Sydney Morning Herald are still publishing story after story by Philip Dorling - stories that have deeply embarrassed or compromised Kevin Rudd, Mark Arbib, Joel Fitzgibbon, and Stephen Gumley, to name just a few, not to mention the US Embassy in Canberra. But we can't judge for ourselves if Dorling has reported accurately or fairly, because Fairfax hasn't posted a single cable online.

On Monday I sent an email to SMH editor-in-chief Peter Fray, asking him why not. His response (read it in full here) makes it clear that the primary reason is to protect not the public, but Fairfax's commercial, interest:

...the volume of material in the Australian referenced cables means we are still mining the source documents. There are, for instance, several potential stories in each cable; to put the material online would be to give access to our competitors in the local market.

That's not a line of reasoning that has prevented The Guardian, the New York Times, Der Spiegel, Le Monde or any other of WikiLeaks's collaborators from posting cables online to support their stories; and it would seem to be in direct contravention of the principles espoused by Julian Assange. Perhaps he's been too preoccupied by other matters recently to have noticed.

Philip Dorling has undoubtedly scored a major scoop for Fairfax. Most of the stories he's writing - and there are goodness knows how many to come - are fascinating, especially to politics and foreign policy junkies. But we're having to take them on trust, and we shouldn't have to. And very few are telling us stuff we didn't already know (Kevin Rudd's a control freak; Defence Procurement is a mess; China doesn't like the Defence White Paper): what they are telling us is that the US Embassy knew it too, often before we did. Surprise, surprise.

Government ministers hold power because their party secured a majority of votes (or it did before August 2010). Nobody elected a single one of the signatories of the Walkley Foundation's letter.

So while we're all enjoying the humiliation of ministers and ex-ministers - a great Australian sport, which right now we seem to be better at than cricket - we should also remember to exercise towards the media's more grandiose claims that other talent for which Australians are supposedly famous: bullshit detection.

Jonathan Holmes is the presenter of ABC TV's Media Watch.