Engadget has issued a mea culpa for “AppleGate” – its announcement that Apple was delaying the iPhone and the next version of OS X for several months. The story, which turned out to be unfounded, lost Apple stock owners an amazing $4 billion with minutes.

Engadget’s Ryan Block had the task of explaining their situation:

Credibility and trust is the currency of our realm, and it’s clear we lost some of that. (And to be 100% clear, no one at Engadget is allowed to own stock in any of the companies we write about.) We take what we do very seriously and would never knowingly pass along information that we believed could be false or inaccurate; in this case, as stated above, we had confirmation from within Apple that this was in fact information that been distributed via Apple’s internal corporate email system. If we had had any inkling that ANYONE could have exploited that system that would have greatly affected how we proceeded.

Engadget’s decision to run a story based on flimsy information is becoming all too common in the blogosphere. As blogs compete for audience, there’s more and more pressure to run stories, even if they’re based on little more than rumors. This ultimately damages the credibility of independent blogs.

Valleywag has gained a reputation for publishing stories that turn out to be unfounded, with its stories on Natalie Portman’s 24/7 “lifecast” and others. Many Apple sites seem to thrive on these types of stories.

When a site like Engadget starts doing this, though, and it costs people (at least temporarily) $4 billion dollars, it’s easy to see that this is a dangerous trend for the blogging world. Sites like Valleywag and Engadget have focused an incredible amount of time and attention from bloggers & podcasters on stories that have turned out to be fake. When this happens, it affects the mainstream perception of all indie blogs and podcasters.

Unfortunately, Valleywag & Engadget’s unfounded stories are a catch-22 for other tech sites. You can treat these stories as unreliable, as we chose to do with Engadget’s iPhone delay article, and risk leaving readers uninformed about potentially important news events; or you can treat them as legitimate or questionable, as we chose to do with Valleywag’s story on the Natalie Portman lifecast, and end up giving credence to bogus stories.

Over at TechCrunch, Mike Arrington comments that AppleGate may prove to be an important milestone for the blogosphere:

“I‚Äôm not sure we (bloggers) understood quite how much influence we really had until yesterday. ‚ÄúAppleGate‚Äù will become an important historical footnote for the development of blogs and the evolution of the news and editorial business more generally.”

If AppleGate proves to be a milestone in the development of blogging, it may be remembered as the point at which bloggers realized that they had become mainstream media, and had earned a level of trust that needs to be treated with care.