It's my belief that Nikon finally catered to the wishes of the wedding crowd. How fast can a bride move that in order to justify the D3's framerate?
This body is a swing at Canon's 5d and it fits the bill nicely. Wedding pros finally get an FX body, bringing a return to the narrower depth of field to Nikon's vaunted primes that the wedding pros are so fond of.
Bringing the SB-900 has also sealed in my mind Nikon's dedication to the wedding pros, those unsung heroes who earn money every weekend with their kit. Nikon already has an amazing lighting system, bringing many canonites over to the fold, with this flash this will be more prominent. I'm loving the full manual interface with selectors to go straight to remote or master. It will be the new weapon of choice.
The add-on MB-d10 also makes this the backup of choice for newsies who have chosen the D3 as a primary body.