Discrete divisions on terrain?

I'd like to present discrete regions on terrain, something like: http://www.slickentertainment.com/tech/dev-blog-53-procedural-goodness-part-3/

Notice how the borders are distinct between the different regions. Notice also that the edges are crisp and sharp.

Can this kind of effect be achieved using the built in terrain? Perhaps with the use of some kind of special shader?

The only other option I can imagine is generating the terrain mesh - but I'm concerned that achieving the kind of crisp edges I'm looking for by playing with UV coords is going to be incredibly difficult.

Any suggestions? Anyone?