Apple Files Patent for “Active Stylus” For Use with iPods, iPhones and iPads
"Conventional styluses are passive input devices in that they are incapable of actively transmitting stimulus signals or sensing a touch-induced capacitance change in a capacitive touch sensor panel...Unlike conventional styluses which work passively by blocking electric field lines between the drive and sense electrodes of a capacitive touch sensor panel, the styluses disclosed in the various embodiments of this disclosure can either act as a drive electrode to create an electric field between the drive electrode and the sense lines of a mutual capacitive touch sensor panel, or as a sense electrode for sensing capacitively coupled signals from one or more stimulated drive rows and columns of the touch sensor panel or both," Apple explains in its patent application.
According to Apple, active styluses allow for more accurate input without driving up the cost. You could say that Apple is trying to reinvent the stylus, but an active stylus would perform the same functions as a traditional stylus, it would just do a better job.
One thing that's interesting to note is that Apple didn't directly file the patent application. The names that appear on the paperwork are Jonah Harley and David Simon, both of which are engineering managers at Apple.