I think I understand the utility of the image of a house in that you start by building the foundation and from there construct the structure until you finish with the roof.  However, for me it is a static model and not as useful as one which depicts the dynamic nature of the Lean Journey.  We are beginning to play with a different model, more of a process model of the lean enterprise process here at the ASQ Lean Enterprise Division as part of structuring our Lean Enterprise Body of Knowledge.