http://www.blender.org/api/blender_python_api_current/ As of 10/11 november 2015 we can now link to the current api docs and not be worr...
March 25, 2013
Vertex Color Map
setting vertex colors
first, run this code only on primitive objects until you understand what it does.
this is for setting vertex colors of a vertex color map
getting vertex colors
getting vertex colors is similar but in reverse, remember that 1 vertex can be shared by several polygons and each polygon can set a different color for that vertex/index. Notice how the plane divided into 4 below has one central vertex which is shared by 4 surrounding polygons, each polygon has a different color for that vertex.
Material from vertex color map
this requires setting viewport shading from solid to texture.