I've been interested in Nike+ ever since I read the Wired article on it.
Here's what I commented:
that article also includes a more precise description of how the device works: 'The shoe sensor's accelerometer measures the amount of time a runner's foot is on the ground, which is inversely proportional to speed.'
i'm seriously thinking of trying this as i plan on moving from walking to jogging. i don't need major accuracy.
another possibility for cheapskates like me who won't pay for the iPhone and it's expensive plan: i'm 95% sure you can use an iPod touch instead. it's not a phone and doesn't have 3G data, but it does have WiFi and can use iPhone apps. touch starts at $229 but requires no ongoing plan.
so, let's see: SportsBand or save that money for the iPod touch, which is 75% more? decisions, decisions ;-)