Figured that it'd be okay to share this here. Sneak peek at the upcoming cover of issue 12.
(http://www.rcsitravel.net/Blog/Issue12-Cov-ColSketch2.jpg) (http://rcsi-publishing.blogspot.com/2010/10/working-issue-12-cover-version-ii.html)
Now, it's the color-mockup, which is used to generate a "good idea" of what the finished cover will look like by laying in flat colors underneath the sketch. Really it's done so the cover can be played around with before putting in all the work of inking and shading.
The finished cover is inked, colored and then shaded, to give it a lot more depth and awesomeness.