Square Enix has pushed back the release date of Final Fantasy I & II Advance for GBA in Japan, due to a programming error in the game. No new release date has been announced.
It's FF I AND II. Same cartridge. They've also added a whole new section full of bosses and monsters from other FFs (Chupon, Rubicant, Gilgamesh, etc.) which they claim to be the size of a full game. I don't know how believable that bit about it being full length is, but suffice it to say, it is a pretty cool extra, and I'm probably going to be buying it solely for that extra stuff.