I like this, but:
*could you add the option to gradually fade out (say over 4 seconds) the end of each 60-second chunk -- and possibly a fade-in at the beginning? It sounds very abrupt at the moment. Also any possibility of allowing the choice of length of chunk? Set it to 2:30 and combine the previous feature, and you have instant music for ballrooom dance. (Sort of thing you'd really want to do with Audacity or Sound Studio, but they're not scriptable.)
*might be nice if you could tie the counter to what's actually playing -- it carries on counting down when iTunes is paused.
*the text 'no shuffle' on the 'shuffle playlist?' dialogue is displaced
*you need a new icon; something with fewer colours and making better use of the available space -- i.e. not rectangular.