http://nikonrumors.com/2011/12/11/nikon-d4-specs-16-2mp-11-fps-102400-native-iso-xqd-memory-card.aspx/
From NR:
Autofocus with 9 cross type sensors that will be operational up to f8 means that the 200-400 F4 with 2xTCIII will autofocus normally on that body...Nikon D4 specs:
•16.2 MP
•11 fps
•100-102,400 native ISO range, expandable to 50 and 204,800
•CF + XQD memory card slots! That's right, the Nikon D4 will have the new Compact Flash XQD memory card slot.
•Compatible with the new Nikon WT-5 wireless transmitter
•Integrated Ethernet in the camera
•Face detection/recognition function that will be working in the viewfinder (maybe some type of a hybrid viewfinder? Nikon had several related patents)
•Improved video, I have no other details on that but my guess is 1080p/30/25/24 and 720p/60/30/25/24 similar to the Nikon D800
•Uncompressed video out through the HDMI port
•Ability to assign the two buttons on the front of the camera to smooth aperture control during video recording
•Improved 51 AF points
•AF detection range will go down to EV-2.0 (the D3s went to EV -1)
•Autofocus system: 9 cross-type sensors that are operational up to f/8
D4 being a TOTALLY different camera than the rumoured D800 with 36Mp seems very logic to me. I wonder and doubt there will come a D4x.