For now, it'll run on the mobile phone only. We're working to make it available on all devices, though. That won't happen for at least a year.
Will it be iOS 5 and up only? I have a very old iPhone sitting around. :) (iOS4)
Unfortunately the bluetooth protocol got a lot easier to integrate into our app in iOS 5, but we may release on other platforms in the future! Thanks for the +1 for iOS4.