A new Apple patent (number 8286103) at the U.S. Patent & Trademark Office shows that Apple is looking at new ways for your to unlock your iOS device -- and, conceivably, a Mac as well. The patent is for unlocking a device by performing a gesture on an unlock image.
Per the patent, the device is unlocked if contact with the display corresponds to a predefined gesture for unlocking the device. The device displays one or more unlock images with respect to which the predefined gesture is to be performed in order to unlock the device.
The performance of the predefined gesture with respect to the unlock image may include moving the unlock image to a predefined location and/or moving the unlock image along a predefined path. The device may also display visual cues of the predefined gesture on the touch screen to remind a user of the gesture.
Here's Apple's background on the invention: "Touch-sensitive displays (also known as 'touch screens' or 'touchscreens')...| Read more »