Blender Vertex and Object Colour Animation (Blender Internal Node Keyframing)
CC0 Public Domain
Here is the node tree: http://i.imgur.com/9p3t19C.png
Each step, a mix shader receives the prior mix shader and an additional colour layer to blend to. This is repeated until we return to the last step, in this case is receiving the original colour layer in addition to the last mix shader.
The last mix shader is then output to a new material which is then output to a meterial output.