I think a Genome shader/map is an interesting idea. While there is a bit of overlap with Ember, I think Genome’s infrastructure for exposing mesh information about the underlying object being shaded (via the ShadeContext) could be really useful. Ember’s texmap on the other hand is going to stay fairly “dumb”. Its just a simple 3D map that doesn’t care about the evaluation point’s normal, view direction, mesh information, etc.
If you’re actually looking for a bitmap when the results are cached at a specific resolution, I think Chad is correct when he says its simply a matter of making an equivalent plane and caching the vertex colors. Did you foresee anything fancier than that?