I have found that my D800 fires my sb600 and/or my sb910 about 1 in 10 times. Sometimes I have to shut it completely off and turn it back on and then it will occasionally fire the flashes. I also noted that the flashes don't fire at the same strength that they do when fired with my d300. I ran a side by side test with the d800 and d300 and the d300 fired them every time and the d800 would fire them once and then not again until after I shut it off and turned it back on again. The strobes fired about a stop too dim compared to the d300.
With this and the image moving during auto bracket and interval shooting, this camera is going back for repair. I still like the rest of the d800 but I have to say it wasn't very well tested before release.