Some links I found interesting:

link 1 - This one in particular contains some links to other threads.
link 2
link 3

if you can use pixel shaders 3.0, you could try this terrain rendering method.
Using a vertex texture for the terrain allows your artist to modify the heightmap image as he wishes, and the changes are "automagically" updated in the renderer (or sort of: you always need to refill the vertex texture data after every update, but it's not a big problem..)

hope this helps :)