I have been letting this story brew all night to try and squeeze every possible bit of information from it. I will leave you will all I have learned since the rumor was first posted.
I think you guys remember EGM stating that the DS would see a spinoff of FFXIII. Well according to this rumor, it looks like they may have been on the right track with the wrong game. The NeoGAFers were at it again, when poster Neo2046 stumbled upon a Japanese blog that had this posted. I edited the image to just show the Nintendo information, there was a bit of Kingdom Hearts II info as well.
Shortly after this was posted, the author of the blog edited the story and removed the info you see above. Now the site simply says FF12. No one knows why the information was edited, perhaps at the request of Square-Enix.
Now there are two big reasons why this Japanese blog can be trusted. The author of this blog also happened to break the news on two other Square-Enix high profile games, Chocobo & the Magic Picture Book and Dragon Quest Monsters: Joker. Has he done it once again with the first news of a FFXII side story for the DS?
Make sure you keep an eye on the NeoGAF thread, more information/confirmations of the title may pop up. Later guys, I am off to bed. I hope your Monday morning starts off well.