This Snarkling continues to parse out what counts as a publishing credit from a previous post:
Miss Snark, What about a number of letters to the New York Times on a topic relevant to the book you are querying about? It's about as hard to get a letter published as it is to find an agent. Is it a joke to mention this?
This is an excellent question because it perfectly illuminates the difference between material for your bio sheet and publishing credits. Letters to the NYT are bio fodder. Jane Smiley writes a lot of letters to the NYT and is published on average of once a month I think. It's a fun fact used by her publicists. And yes, it's hard to get a letter in the Times.
Letters to the NYT don't count (at least with me) as publishing credits. They're not a joke though, and if you mention them it doesn't put you in the nitwit class.