Sadly the iphone Bluetooth is crippled to only work with other iphone.....BACK ON TOPIC <_<
Bluetooth? Wrong.
Moron.I'd imagine an iPhone (and perhaps even Android?) app that connected via WiFi to your computer and allowed you to change weapons and use items would be rather cool and somewhat practical, but not by very much.
However, it would still be miles more probable than a real Pip-Boy. The chances of that being possible are somewhere between "a snowballs chance in hell" and "unpossible".