Quote - "I am more interested in the "hyperterrains" myself... is it similar to hypertextures ? "

No. Hyperterrains is an expression created (as far as I know) by Quadspinner to designate primitives (or metablobs from primitives) to which a rock material with displacement was applied. That displacement is then baked, in order to create additional polygons and then another rock material with bump is applied. It's a simple procedure, used for years by many people, but that was now made popular by Quadspinner.