D2x pop up flash?

[krviera]

Besides the fact that many don't use the pop-up flash, another reason for not having it is that it provides for better seals around the camera. Pro cameras come with a lot better weather protection than the regular consumer or prosumer cameras and not having the pop-up is one more place the you don't have to worry about getting moisture through. When you get your D2X, you'll see that it is built like the F5, with all the rubber seals to protect it from the elements.

[speedydave]

And to add to what Keith said, I believe that they don't have a built-in flash in order to save battery life (not sure how much truth there is to that, though).