Hey Nichoid great link thanks!! That will be useful in the future.
The workflow I mentioned like this guy is doing(link below) is more of a 2D still matte type.
And the ambient occlusion is only a normal Z render. Not real occlusion.
One could export it to do displacements and occlusion in XSI, but then the whole idea of a speedy workflow gets lost I guess.
But if one export it to photoshop and colour it there with multiply blending mode(highlights and shadows), one can do a mountain and landscapes in no time. No UV etc.
http://206.145.80.239/zbc/showthread.php?t=35764