We're still waiting for the first Apple OLED product, but in the meantime the company keeps filing OLED related patents. The latest one deals with brightness control on OLED displays. In OLEDs, controlling the brightness isn't straightforward like in LCDs (in which you simply change the brightness of the BLU) - as you control each pixel by itself.
In Apple's new brightness control method, image data will be converted from a "frame buffer encoding" gamma-corrected color space to a logarithmic value. In the logarithmic value, a digital dimming control value may be subtracted rather than divided. This can be converted directly to an analog OLED pixel brightness control signal, without first being converted to a linear digital value. This results in a simple brightness/dimming control - which means it'll be more efficient and requires less hardware.