Two posts on gigantor-sized fabs this week! The Information Sciences Institute's Dr. Behrokh Khoshnevis's Contour Crafting Technology enables fabbing on a building-sized scale. Apparently the Doctor plans on releasing the USD$1.5M machine very soon, and we will soon see if this type of "personal" manufacturing will work. Be sure to check out the videos, especially the "Video of operation of actual Contour Crafting prototype machine".
We're definitely a long way from having entire complete buildings being simply printed - but this technology will permit onsite fabbing of the basic structure, leaving a portion of the construction for manual labor. It likely won't do electrical wiring or complex installation of tricky components such as furnaces, insulated windows or intricately carved Italian marble lobbies. But I am sure those too will come in time.