It seems to me that since the iPhone already has anaccelerometer, this app should work with any shoes without special hardware. In fact, apps like RunKeeper are already available on the App Store. What value will Nike provide?
Yes, we will just need to buy the new Nike shoes with a slot to fit your iPhone in.
Just kidding, the image of tying strapping an iPhone to your shoe just cracked me up. I have no idea what can or can't be done with the iPhone accelerometer with this, if it would work just as well tied to your waist or on an armband.
I would prefer GPS (especially if the new iPod Touch has GPS), but I don't run on a treadmill.