Using the MAC address as a unique identifier alone seems like a terrible idea(that is, without other secret, constant data included in the hash, similar to how UDIDs are generated.)<p>Your device is literally broadcasting your unique identifier to everyone in a several hundred foot radius.
It's also quite easy to just grab the MAC address manually: <a href="http://stackoverflow.com/questions/677530/how-can-i-programmatically-get-the-mac-address-of-an-iphone" rel="nofollow">http://stackoverflow.com/questions/677530/how-can-i-programm...</a>
Title and project name are misleading. This identifier is not unique per device, but unique per device+bundle identifier. This means different applications on the same device will generate different identifiers. Please, stop upvoting without reading (it's mentioned in the project README).