Mostly extra contrast, some fake ambient occlusion, the line drawing on top of the rendering, and some effect to give it a little bit of a sketchy feel.
The line drawing: You can do this in VW, but if you want to use the Artistic style of VW the lines can become a sort of pixelated if you lay them on top of a rendered viewport.
Everything done in VW is always better. Maybe we can ask Jim to combine VW en PS ;-)