When is a bestseller not a bestseller?

A very interesting post today on the blog of US thriller writer JA Konrath: http://jakonrath.blogspot.com/2011/03/lol-nyt.html He notes that although the famous New York Times Best Sellers list now includes ebooks in its sales calculations, it still excludes self-published writers, regardless of the number of sales. Konrath calculates that he has sold enough books to make the list, as have authors such as Amanda Hocking and John Locke. In fact on Amazon.com, Konrath's The List is currently outselling the Kindle version of the New York Times itself!

I can understand why the New York Times would want to exclude free books from its list of 'sellers' (many of these are self-published) or even why it might be sensible for it to exclude any book priced under a certain amount. But I can see no logical reason for excluding self-published authors. A sale is a sale, regardless of the book's publishing arrangements.