dang, just relized Blue Marble stopped offering the Bump, Spec, topygraphy, and many other maps…glad I got them 
(I have the 52000x26000 res maps)
I have seperate Bump, Color, Spec, and cloud maps, all at 52000x26000, however since blender can’t use them (Big crash, LOL) I resized to 8152x4076.
So yes, seperate Bump map. Note how rivers even have spec, thats due to the spec map I’m using, high res = good thing.
and yes, the atmosphere is a blend texture, normal mapping, X - - coords, alpha, etc.
as I stated, I’m still working on my tutorial for this, and that will include the JPG maps I’m using, be forwarned, they are NOT small, the cloud map is 16 megs, the color map is 24 megs, bump and spec are about 4 megs each.
Though I will most likely compress the images and knock them down in size. Actually, for the cloud and color maps, I can point you at Nasa’s site for the blue marble maps…
oh, and I’ll include the night map, not the color one on Nasas site, JUST the lights, no texture. (Looks sweet)