I know what you mean, but I am pretty sure that we won't see procedural erosion in Vue or Terragen any time soon. As a frequent (but silent) reader of the Planetside forums I remember a thread where Oshyan said that Procedural erosion is not possible yet, because the amount of necessary calculations would bring even Pixars workstations down to their knees. Just think about how long a single erosion operation in Geocontrol 2 or Worldmachine 2 lasts - up to several minutes on really fast PCs. Now think about what that meant for procedural erosions as opposed to those bitmap based erosion operations. Rendertimes would rocket into the sky. I think that e-on is doing research on that kind of stuff, but it's just too complex for PCs in the year 2010 ;-).