In spite of its $600 price tag, Sony famously took a huge hit with every PS3 sold. With the exception of Nintendo, it's common practice for console manufacturers to sell their consoles below cost, subsidizing hardware for profits made up by software and accessory sales. PS4 continues that trend.
Sony's Masayasu Ito wouldn't reveal exactly how much the company is losing with each PS4 sold, however he said that the company is expecting a profit "on an average user's initial purchase."
Eurogamer claims that Sony loses approximately $60 on every PS4 sold. However, the sale of a PlayStation Plus subscription and one launch game will go a long way in making up the difference.
Nintendo made similar comments at the launch of Wii U, pointing out that all it took was the sale of one game to sell their latest console at a profit.