I'm quite busy with several other topics and OpenSCAD was the solution for one of the problems. I figured the solution in a break from the current topics - I need from time to time to exercise some other parts of my brain :P.
So instead of putting this on my stack and waiting about one year to push it forward... please feel free to submit it yourself. Anyway, the code was based on your sketches :P.
@Brad - the ideea was to be able to draw a cylinder between 2 arbitrary points. The spheres were there as placeholders for the ending points. But your solution gives me some ideas, as it can be used for offseting some convex polygons - maybe this could be quicker than computing the minkowski sum.