What some people may be missing is that APPLE, is designing and thinking of not ONLY doing this but also making a portable headphone. Apple's patents look close to nothing like final products so don't worry about the patent picture.
Wired does bring to point that Apple is showcasing many sensors that they have patented for use that could be used on the headphone but my concern is, that none the less, you are puttting an amplifier and a "speaker class" driver in a headphone in terms of how much dB of sound it may produce. I would still be a bit hesitant to put that on my ears in the case that something does happen. I know, this is like worrying that the volume on your PMP will sudden somehow boost to Max. Most have thought of that before but of course it never happened unless one physically did something.
I'll be interested in seeing what headphones Apple will be using, their drivers, how they sound, and what amp and all those nifty details that Apple may use in the headphone IF this comes to fruit. Many Apple patents never come to the consumers hands in case you are curious.