The confirmation of the problem as well as details of how it may effect images taken with the camera is provided on the Nikon support centre website here.
Nikon confirm that the problem occurs in 'a small number of early production D200 cameras' and will appear as vertical lines in images containing extreme contrast when the image is viewed on a computer screen at sizes above 100%.
They also go on to say that the the banding problem is not an issue at ISO100 and that the appearence of the pattern may vary depending on the sensitivity setting used. As a guide they say that images printed at a size of A3 or smaller will barely display any signs of the pattern at all and it will bear little impact on general photography and printing.
Finally users who experience problems with this pattern occurring are asked to contact their nearest Nikon service representative. They will adjust the image output level so that the pattern of lines will become virtually undetectable.