One mark of a trustworthy pundit: not merely acknowledging a mistake—in this case, relying on information that turned out to be questionable—but actually notifying readers of it.
Last year Kathy Shaidle, who has a nice line in myth-puncturing, linked to research indicating that those notorious "No Irish Need Apply" signs were, in historian Richard Jensen's words, "extremely rare or nonexistent." Since then, however, as Obama voter Megan McArdle* reports, high-school student Rebecca Fried has unearthed "lots of examples of both 'No Irish Need Apply' advertisements and newspaper accounts of 'No Irish' signs."
Alerted by Ed Driscoll to McArdle's post, Shaidle, in a post called "Dammitdammitdammitdammitdammit,"** quoted it and pointed to her own column citing Jensen's now-apparently-refuted work. Many in Shaidle's position would've stayed mum or made excuses; kudos to her for valuing truth above pride.
*I respect McArdle, but her choice in '08 should always be kept in mind.
**As any frequent reader of Shaidle's could tell you, a more forceful title wouldn't have been out of character.