Apple has submitted an application to patent an "optical stylus" for use with future touch based devices, leading to speculation that the next iPhone or iPad could include stylus support. Competitors HTC and Samsung have both released devices featuring stylus control, but Apple's potential product is far more complex, featuring haptic feedback, an on-board speaker, and an optical sensor, all transmitting data back to the device via short range wireless communication.
It's clear from the patent release that Apple's stylus places a focus on enhancing the experience already found on touch devices, specifically through the use of haptic feedback.
An excerpt from the Apple patent describes "an input device capable of generating haptic feedback may help a user navigate content displayed on the display screen, and may further serve to enhance the content of various applications by creating a more appealing and realistic user interface."
If Apple was to include a stylus with its next iPhone - or more likely, the next iPad, there is going to have to be a major redesign in the works, since the device needs to be able to house the stylus and current models are incredibly thin. On the other hand, Apple could market this device as an accessory, eliminating the need to radically change the design of its devices, and those who want to use a stylus will have the ability to purchase one.
It's unclear whether or not Apple's optical stylus will ever materialize, as this patent was originally submitted in 2010. However, Apple has a track record of patenting technology for use in the more distant future, such as its mobile hydrogen fuel cell. Thanks to the fairly strong sales of Samsung's Galaxy Note, Apple may decide it's time for the optical stylus to come to market.
Source: US Patent office via Unwired View, Patently Apple