Playbutton is a wonderful idea that would make music collectable again and give artists back the ability to sell an album experience instead of just letting people cherry-pick individual tracks. Music piracy would still be pretty straightforward, but this idea taps into the desire to own and display something that represents what you love. They could be pretty cheap too and – so long as the audio quality is good – be a huge hit.
Would be nice to see a design with an iPod shuffle-like clip instead of a pin.