It's a classic entry in the pantheon of RPGs: Square's Secret of Mana for Super Nintendo is widely regarded as one of the finest games in the genre, even after all these years, but other than the less well-received Children of Mana and Heroes of Mana we haven't seen the series reach the DS. It looks as though that injustice isn't about to be rectified any time soon, as Square-Enix has announced the original Secret of Mana is heading to iPhone, with no other formats mentioned.
If the iPhone can receive a translation of one of the true greats in the RPG world, it begs the question "why not the DS?" Larger titles such as Rayman have made the jump across to DSiWare intact, so it's certainly not a size limitation. Nintendo's resistance to ports of titles from its previous hardware is most likely the largest contributing factor here – were Square-Enix to release a perfect conversion of a Super Nintendo title the floodgates would be open for other re-releases.
With Nintendo keen to offer brand new games on DSiWare it looks as though this is one title we won't be seeing in the DSi Shop any time soon. Still, you can get it for Virtual Console, so chin up, eh?