The thing is, I am!
You might want to think about working from the most current version of his shaders (poke around in 'downloads'), rather than the dated, and somewhat badly-commented version in GPU Gems...
I have started the SkyFromSpace shader from scratch about 6 times now, once from the GPU Gems article, once from the current version, once from the article in nvidia FX Composer, trying to debug it, again from the current version in fx composer, once from someone else's source code on here, and once from Hyunkel's code here.
I figured out why I didn't get the orange transition. Before I got the lightScale value right, the whole sphere was lit up so I multiplied the resulting diffuse by the lightAngle to make the far side of the planet dark. Now that the lightScale works correctly though, it was fading the diffuse out before the transition.
Now that it's got the right value, the far side of the planet turns dark on it's own.
I'm kind of clueless about the SkyFromSpace shader though...I guess I will take another stab at it sometime.