The current issue of V-Jump magazine has a full page dedicated to Square Enix's announcement of releasing Final Fantasy I + II (as one title) for the GameBoy Advance. The title will be made available in Japan during the month of July and will cost consumers 6,090 JPY.
Link >> FF I + II Magazine Scan
Final Fantasy I will contain an additional element called "Soul of Chaos". Details are still sketchy, but it has something to do with a great power that can either be used by gamers or by monsters. Also, it has been confirmed that the magic of Final Fantasy I has changed from the frequency system to the MP consumption system.
Final Fantasy II will have an extra storyline called "Soul of Re-Birth" which will dwell on the protagonist of the game. The new story comes with new enemies to battle, new items and much more.