Those who think blogs are dangerous and bloggers are people who only set out to destroy reputations will love this story.

Just before midday NY time yesterday, gadget blog Engadget posted that Apple’s iPhone would be delayed until October and the new Leopard operating system for Macintosh computers delayed until January 2008.

You can see stock market reaction to that news in the Google Finance graph here – Apple’s share price plummeted, immediately wiping $4 billion of the firm’s market value before recovering some 15 minutes later.

The trouble is, the news was untrue.

According to Engadget, this is what happened:

A trustworthy source supplied us with an actual internal Apple email that went out to thousands of Apple employees earlier today (published after the break). The fact that this was an email sent within Apple’s internal email system to its employees is not in question. Let us reiterate: this was an ACTUAL email distributed within Apple’s internal email system to Apple employees.

As it turns out, the internal memo Apple employees received was actually retracted by Apple shortly after it was sent out. (Also published after the break.) We received confirmation from Apple PR that this initial email sent out to Apple employees was incorrect, and they let us know that the iPhone and Leopard are both still on track, and should meet their expected launch timeframes.

Engadget is a professional blog, with content written by experienced and skilled bloggers. That’s what makes this faux pas all the more surprising – it looks like Engadget saw a scoop and rushed to publish with the hot news without getting some kind of verification first.

This opens the door to the long-running blogosphere debate about blogging vs journalism. It includes beliefs that bloggers don’t question things before they post, whereas journalists always verify a story before they publish.

It’s never as black and white as that.

But whatever. In this case, Engadget clearly took at face value an email supposedly sent within Apple by an Apple employee (presumably) and which was sent to them.

Indeed, this is from Engadget’s original text:

This one doesn’t bode well for Mac fans and the iPhone-hopeful: we have it on authority that as of today, the iPhone launch is being pushed back from June to… October (!), and Leopard is again seeing a delay, this time being pushed all the way back to January.

A bit unfortunate for Engadget that they used the phrase “we have it on authority.” Not much authority, as it turned out.

One of the first comments to Engadget’s original post is this smart one:

Um, sources please, Apple has nothing on this their press site. I’ll believe it when I see more solid proof.

Mistakes can and obviously do happen, although not always with such potentially serious consequences.

Incidentally, there is no suggestion here whatsoever that Engadget set out to do anything like the wording in the first paragraph of this post. For those who think negative thoughts about blogging and bloggers, note that such mistakes happen in the mainstream media all the time.