Saying "you are the product not the customer" is not only popularist, but wrong.
Think about Skype - most of their customers don't pay, but they derive value FROM Skype - AND they add value to the paying customers.
Simplifying complicated markets with statements like "you are the product not the customer" is a disservice to the discussion.
For example, The New York Times offers some value to the owners of those eyeballs, but note how they work: they lay out the advertising first, then what's left is what they call the "news hole" and they put some stuff there. The news hole lets them farm the eyeballs. (The ripe juicy professional-managerial variety.)
This is not something programmers like to think about, so they tend to wear ideological blinders. They don't simply observe the money flow: who is buying and who is selling? The eyeball owners are not participating in a market transaction as either buyer or seller. Their attention is the product.
Think of sports teams - advertisers pay their salaries, but when they are performing on the sports field advertisers are irrellevant.