Harry Potter and the Sorcerer's Stone originally appeared on the New York Times Bestseller list back in December of 1998. The impact of Potter's popularity led the NYT to creating two new lists so other titles could make the list other than Jo's stories.
Now, almost ten years later, the May 11th edition of The Sunday New York Times will be free of any Potter novel. Check out the NYT's Book Blog for more.
Once JK Rowling's Potter Encyclopedia is released, we're sure Potter will make a comeback. Thanks to Pruneau for the tip!