In the past, we went through a list of products compatible with Nikon D900. Some of them could be a typo or just an easy way to get Internet traffic. Today, a NR reader sent me those pictures of Phottix Titan battery which is compatible with Nikon D900 - clearly written on the back of the package (click on image for larger view):
On the manufacturer's website, D900 is not listed as a compatible cameras.
I know, after the D700x sensor post, this news doesn't make it any easier to guess what's coming next. The actual model number is not important, but it can give us a clue what the camera would be (D700s->sensor from D3s | D700x->sensor from D3x | D900-> completely new camera).