Scans from the V Jump magazine report that FFIV:DS will be out on December 20th 2007.

The first page shows off the updated Active Time Battle system with more battle information available on the bottom screen as mentioned in the interview before. There's also the new "Decant Ability System" that allows skills to be inherited from a departed party member. You can then set the skill and use it in battle. Here Cecil inherits "Sing".

And here's CG renders of the lovely Rydia grown up and Yang, the head of the Fabul Monks. It also looks like there will be a new summon called "Pouchika" where you can design its face and customise its abilities.

The new content sounds like fun. I hope they include some other pre-order goody and not another DS set but knowing SE, they probably will prepare another LE bundle.