Here's an early autumnal contender: Virginia Heffernan's entirely anecdotal story about a massive Facebook Exodus. How serious is this Facebook exodus? Heffernan explains:
The exodus is not evident from the site's overall numbers.
The exodus is not evident from the site's overall numbers! Some trend!
My understanding is that trend pieces should at best agree with relevant statistics, or at least be compatible with relevant statistics, or perhaps include no statistics whatsoever to preserve the integrity of a couple scattered observations. But Heffernan bravely spots and identifies a trend suffering from something worse than no evidence -- the preponderance of the evidence suggests the exact opposite thing!
The New York Observer debunks the piece (Facebook users are up more than 150 percent this year) but really, they're just re-citing a traitorous fact acknowledged in the third paragraph. The trend piece readily debunks itself.