_{no, this wasn't done with Poser 8, fyi. Although I did just get it today}

Yes, those are lines you see. I acted on a hunch and did a second render pass using falloff shaders—which in Poser, is really just the root material with it's ambient node on, diffuse and specs off and an EdgeBlend node attached to the ambient node. Anyway, I found out that when you bring the resulting render into Photoshop, and use a combination of the High Pass filter and the Levels adjustment layer, you get pretty decent line-art with line values and all. The only draw-back is that in order to prevent the "jaggies" created by Levels, you have to render at twice the size of the original and then shrink it down.

So this isn't the only thing I've been working on. I've also been working on a more "traditional" appearance for celshaded renders out of Poser. I'll post those when I get the chance.