I hope they come through for you. I had an order placed with Amazon that had an expected delivery date too, but it was never met. I ended up getting one through Onecall.com and cancelled my Amazon order. Onecall seems to be able to get them when others can't and a very short waiting list. Their customer service is also excellent.
It seems like a D800 shipped recently should have the latest firmware and also a higher serial number than yours. I got my D800 at the end of June. It had the latest firmware installed, and the serial number is 3023xxx. I don't know what Amazon does with returned cameras, but you might want to check the number of shutter actuations to determine if yours is actually brand new.
Just checked, shutter count of one on the first picture I took last night. So that is good news. Someone could have gotten it and sent it back without opening it. The packaging looked good and everything in it. The camera even had that new camera smell.