I think he was referring to the fact that people talked about Amazon, even outside of geek circles. It was the first big online retailer - before that, people just didn't buy things online. Amazon changed that by generating suffcient word-of-mouth buzz. That buzz in return allowed Amazon an easier job negotiating with publishers to distribute their books, which made Amazon cheaper than bricks and mortar stores, which increased the buzz, which allowed them to negotiate even better prices.