That's not a stylus, this is a stylus
SJ didn't like a stylus for a PDA and I tend to agree, after years of replacing the wretched things when I lost them from my Palm.
I'm a big fan of alternative devices for input, owning an original IBM CrossPad and many others since.
This patent is interesting and if any of the 'wits above commenting had bothered to read it, explicitly calls out the need of other devices to use a special background tablet or paper.
The various pens I researched and blogged about in 2010 http://aussiedesignedsoftware.com/blog/?p=185 either used the Anoto paper (LiveScribe) or some kind of clipboard attachment from which the pen took its location.
Apple's patent talks about establishing the four corners of the working area then scribbling within.
I suspect it collides with the Lernstift from VibeWrite https://www.youtube.com/watch?v=nstzSSvZElU#t=29 but probably pre-dates them.