'Shoulder surfing' is when someone with less than honorable intentions looks over at your phone while you're entering sensitive information, such as a PIN or password. It's a serious problem, and Apple wants to make it less likely to happen on an iPhone.
As spotted by AppleInsider, Apple has recently filed two patents for dealing with the issue. The first one details a "privacy film" that includes a "light-blocking layer" as one of the substrates in a phone screen, ensuring that you can only see light from the display if you're looking directly at it.
