I have been trying to figure this out for a little while, so thanks very much for the info. I think the right-click to preset option must be gone, because I can't find it or I am blind, but I was able to find the preset in the attributes for the render layer.

As far as I can see, this causes the same thing as what gubar suggested (i.e. assigning mib amb occlusion texture to the out colour of a surface shader).

Only trouble is... when I try gubar's method, I get a black background with all white where the objects are, similar to what an alpha channel would look like. When I try the render preset method, I do get some shading where there's supposed to be shading, but the background is white, and almost everything else is white too, not much shading going on. I've tweaked some settings, but I can't figure out what's different between these two options; they should do the same thing?

Thanks for any thoughts. I'm looking forward to finally rendering something instead of screenshots all the time.