The Source engine has Wrinkle maps, which Valve define as a "shader to make per-vertex texture changes when the [shape key] is applied. They are typically used to add fine wrinkling detail to a character's skin."
Basically when vertices are compressed or streached, it changes a part of the texture.
Can I do this in Blender with any automation?
Or is the easiest way to just set up a ridiculously complex system of drivers and custom alpha channels to manipulate shades when the shape keys are changed?