According to the group's progress table, only a few sections still need translation (e.g. monster descriptions, location names), so a full and final English patch doesn't seem too far off. A Translation Wiki is also available for those missing bits or for those of you who'd rather pass on using the patch altogether.
Square Enix has yet to announce its plans for Final Fantasy IV's release outside of Japan. Our best guess? Mid-to-late 2008.