At the risk of reviving a dead thread, I just wanted to throw my 2c in.
I'd rather see an in-game addon rather than an app for any mobile phone. Some people have iPhones, others have Android platforms, others have 'Others'. But everyone seemingly uses GearScore these days.
GearScore won't go away, even though everyone hates it.
Please release an addon. It's long past time for Wow-Heroes to stand up and take its rightful position at the head of gear optimization.