Director Guillermo del Toro popped up over at The One Ring to tease with the announcement that he'd soon be back with the real announcement :
In a few days there will be a BIG announcement (big for me, at least) that is not-Hobbit related. BEFORE anyone starts wondering the usual "how does he have time?, Is this detracting from The Hobbit?" etc. It is a project that started over 2 years ago, before The Hobbit and will render fruits in the mid-term, not intruding on my Hobbit duties. Rest assured.
The key letter is "D"
As in ... 3-D? Or Deadman? Or ...
We honestly have no idea—but let the speculation begin!