Grantwood Technology has announced the release of its new Tuneband for iPhone and iPhone 3G. The Tuneband is an armband case that secures the iPhone to the user’s arm during exercise, while allowing for full access to the device’s screen, controls, and ports. It consists of a flexible Velcro armband strap designed to accommodate both small and large arms, a silicon case to hold the iPhone or iPhone 3G, and a low-tack, cut-and-peel screen…