Apple filed a new patent for a glasses-free 3D device that uses multiple transparent display layers. The different layers would actually allow for visual depth to be seen by the users.
Apple's patent specifically mentions OLED panels as the technology used to make the transparent displays: "The use of OLED panels may provide an advantage over traditional display devices, since OLED panels do not require a backlight to function, and may therefore be much thinner and lighter than backlit display panels. OLED panels are further capable of displaying deep black levels and can naturally achieve a high contrast ratio."
These aren't the first OLED patent applications from Apple. In February 2011 the company filed three different OLED patents, the main one being an OLED with an integrated touch sensor.