This is strictly in the rumor category but it looks like Nikon is about to release a new high end DSLR. According to the rumor, the D4 is a 25 Megapixel, FX sensor body with 6 frames a second shooting capabilities.
The big question would be the low light / high ISO capabilities of the camera. Will it be able to match the fantastic low light capabilities of the D3 and D700?
Time will tell.