Late Thursday night, the Apple (AAPL) rumor site called, appropriately enough, MacRumors, picked up a Japanese report that the company had scheduled a special event on Wednesday Sept. 7. Could this be the launch of the long-awaited iPhone 5?

By Friday morning, MacRumors’ report was the lead item on Techmeme, the online news aggregator that is for Silicon Valley tech writers what The Politico is for inside-the-Beltway political journalists.

We called Apple public relations to see if we should book a flight to San Francisco. They were cheerful but unhelpful.

No matter. The MacRumors story was soon joined by no fewer than 49 others, most purely speculative, with nothing to add but guesses about what might or might not be unveiled at the putative event.

Then, at 11:43 EDT, The Loop‘s Jim Dalrymple, on no other evidence than the word of his unnamed sources, posted a brief item declaring the rumor false. Dalrymple’s sources within Apple being what they are, however, his story carried a lot of weight. By 6 p.m. it had replaced the MacRumors piece as Techmeme’s lead item and was trailed by 19 more headlines.

Typical follow-up story: Business Insider’s Apple Not Holding iPhone 5 Event On September 7th, a word-for-word reposting of Jay Yarrow’s earlier item about the MacRumors piece topped by a one-sentence update: “Apple will not be holding an event on September 7, Jim Dalyrmple at The Loop reports.”

And there you have it. Another day on the Apple beat.