Museum of unintended consequences/Cross recommendations

From CSWiki

According to The New York Times

In January, Walmart.com issued a public apology and took down its entire cross-selling recommendation system when Web customers who looked at a boxed set of movies that included "Martin Luther King: I Have a Dream" and "Unforgivable Blackness: The Rise and Fall of Jack Johnson" were told they might also appreciate a "Planet of the Apes" DVD collection, as well as "Ace Ventura: Pet Detective" and other irrelevant titles.

This is certainly an unintended consequence of the mechanism used by Walmart's cross-selling recommendation system. I wonder what actually happened.