They registered the trademark in North America & Europe, and also picked up the matching domain name.
No further details have been released, but it wouldn’t be hard to imagine that this could be a title heading to a Nintendo format. The subtitle could hint at a 3DS incarnation such as multiple dimensions or perhaps something to do with the Wii U’s extra screen. It has been rumoured that Square-Enix will unveil the next numbered Final Fantasy for multiple formats including the Wii U at E3 2012.
The main Final Fantasy games haven’t landed on a Nintendo format (outside of remakes) since Final Fantasy 6.