FFRing also says (via Japanese translation) that the game will be a 3D title, and it will feature a storyline concerning five pairs of warriors who fight to the death for the right to eternal youth. Each game stage will consist of a ring of battles with a boss in the center, and some choice in how the player takes on enemies -- more challenge for more risk.
It sounds intriguing. Square Enix has been seeing some success with its older titles on the iPhone, and we know it's got a few original titles already in the pipeline for Apple's platforms. It'll be great to see what they can cook up for the App Store.