Jeff Bezos revealed to the BBC that Amazon makes no profit off the Kindle Paperwhite and Kindle Fire HD. Both devices are sold at cost, which means, both devices' price is how much it costs Amazon to make them.
That selling hardware for no profit is certainly much different from Apple's strategy (they make a profit on every iPhone and iPad sold) but not so different from video game companies who've traditionally sold their consoles (Xbox 360, PS3, etc.) at a loss. The thinking there is to make up the profit lost in the console with the cost of games and peripherals. That's the same with Amazon. Use a Kindle and you'll be buying stuff through Amazon. It's like Amazon is providing everybody with slick shopping carts in tablet form.