This will not be the same game as what was released on the Playstation Portable, as the iPhone and PSP are different platforms, you can’t treat them as the same. Going to a new platform, you will need a new and different experience. This will allow them to be able to fill in the gaps with the series world view.
From what I get on the article, it sounds like this will probably take place sometime after 3rd (the story between FC, SC, and 3rd is so tight-knit), and help tie together more elements of Zero no Kiseki.
The original article didn’t have any concrete information but said that this version would have social and online elements added to it. Examples that Taka included were special moves with friends, or giving/receiving items to and from friends. For social elements, having shops- selling weapons and armor sounds like a plausible plan. Then through the lobby, perhaps getting friends to join you on quests and the like.
They won’t be able to bring the graphics straight over from the PSP version, as the PSP has a smaller resolution than the iPhone and the graphics would either not fill the screen or would not look good. They have been considering how to handle it in horizontal or vertical modes.