I've been trying to recreate the Terragen Surface look for quite a while. This image is the closest I've come so far (I did not care about the overall look of the image, it was just for testing:

Recently I experimented again with some alpha layers and an ecosystem. The picture below is not yet finished (e.g. the mountains in the background and the whole object placement) , but it's interesting nonetheless what you can achieve with Terragen-like materials and Ecosystems at the same time.

I have a Tutorial in the works about the discoveries I made. But compared to Chipp's images my attempts seem to be rather foolish.