Call me stupid, but I do not see how that would work. I would very much appreciate an example. It's pretty important that this solution works on IE6 too, so if I were to make an image with only the shadow I would like to use PNG (which isn't supported by IE6), because GIF is really bad when it comes to this in my opinion.
I might put together a quick example for you during weekend but don't take it for granted, I'm pretty busy atm.
Yes you could just set the shadow as the background repeat-y for a wrap DIV If IE6 users don't get the same look thats their fault, I guess you could add a png fix anyways. Or you could add the shadow for the gradient as a background for the header and make the header height total the gradient height, and then use a negative top margin for the rest of the layout to push it back up, so it doesn't matter if the gradient is longer than the header Then you would just have the shadow for the main background colour as the background of the wrap.