Mine doesn't make any noise.
Yeah unfortunately I don't hold much hope in getting a "true" opinion online. I do believe you hear no hum from the display, but I can't guarantee myself that I won't hear a hum. This is based on my testing two Apple 23" Cinema Displays and both humming at less than full brightness. I've only found one or two instances on different forums with other people reporting the same thing. Therefore, most people just don't hear it or have too much ambient noise from their desktop computer etc to even notice it. I use a laptop and silence is a must....
But thanks for letting me know you hear no hum. It's definitely pushing me closer to getting a Planar. Just wish someone here had used both the Planar and the Apple and could tell me that the Planar is at least as good as the Apple, which is stunning..