But, the house does look a lot like the Arango House built by John Lautner, one of the premier architects of the mid 20th Century. It resides on the side of a hill in Acapulco, Mexico. I hope that later this year more information will surface as to whether or not any particular house was a model or inspiration for the one in the movie. For more on the movie architecture, view a video that Yahoo released of the director giving a short tour of the set:
Additional Lautner factoid: his Elrod residence (which is also similar to Stark's house) is the round concrete house used in the Bond movie "Diamonds Are Forever".