Thomas Jourdan has created Innerworld, a node based landscape generator script for Blender.
InnerWorld is a landscape generator running inside Blender. Terrains are generated from Blenders internal noise functions and external height fields. Using an graph editor different noise sources and operators can be used to define a production line for the mesh creation. The landscape generator can be used to fill the world with objects dependent of the terrains hight and slope.
The script comes with three tutorials:
It looks like the project hasn't been very active lately, but with some luck this extra attention could give Thomas the motivation to pick up his efforts again.