This is a G+ community started by some teachers in other NESA schools - you might be interested in their resources and/or joining in ont he convo! (your ipod touches will certainly have much in common with their iPad chat...)
This company is developing sensors that will provide feddback back to your iOS device. Right now it has one for golf but they are making one for Tennis and Baseball as well.
"GolfSense™ is a system (wearable motion sensor + free mobile app) that helps you analyze and improve your golf swing. Attach the GolfSense motion sensor to any golf glove and swing away to get instant feedback and helpful tips on your iPhone®, iPad® or Android™ device."
Although this article starts off about homeschooled children coming into the gym, it continues with information about great PE programs in the US and how they are changing.