I've pushed the core infrastructure. No scattering is available yet, at this stage it's more for you to test and check that there are no regressions (quality and speed wise). I've not yet converted the GPU rendering interfaces, I'll do so when the CPU interfaces are tested. They will probably change because I'm not satisfied with the inhomogeneous volumes handling.
If you want to prepare exporters for scattering support, it's going to be extremely simple. Scattering volumes will have a material attached to them so all you will have to do is embed a material selector in the volume configuration. I'm going to create a few materials specifically designed for scattering, but they'll obviously be available as standard materials too (and vice versa). Will be quite fun to play with I guess.