I can confirm that Second Life uses its own core software. Although it is technically possible to import geometry, in practice it is not worthwhile; Second Life is entirely based around what they call "prims," platonic objects that act much like C4D primitives (plus additional modifiers). It isn't low-poly, per se; the stuff is converted to tri's on the user-side client. But it is very specialized and automated importing seems unlikely to ever be efficient. Second Life users do go through a LOT of textures, and there is much buying and selling of same. I should perhaps warn that their take on IP issues is similar to that of eBay's. Another possible entry into Second Life is that they go through a lot of animations. Unlike the specialized geometry, Second Life's avatars will import standard BVH files -- I have heard talk that the programmers went out of their way to make export from Poser and import into Second Life as seamless as possible. I don't play, but I have a friend on the staff.