I'm not sure if it's there hidden somewhere but I thought that an ambient occlusion node would be super useful for color masking in shaders. Ideally, it would give you an option to look only for occlusion within a given distance and sampling/quality settings. I imagine it would help to achieve very realistic shading with minimum effort.
Ambient Occlusion is a mode for the Enviro Light, but I don't think there's any way to access the shader ouput to re-use it in other ways in the scene at this point. Something to consider for the future as I agree it could be quite useful.
- Oshyan
Good idea...hope to see that in the future...give realistic renders a leg up for sure in the shadows