I'm not sure if this has anything to do with green building, but I think this one room apartment – described in a recent New York Times article – which can be transformed into 24 different rooms, from a kitchen to a spa to an entertainment room, is very interesting. This flexibility might find some traction with the "small house" movement:
This room -- the "maximum kitchen," he calls it -- and the "video game room" he was sitting in minutes before are just 2 of at least 24 different layouts that Mr. Chang, an architect, can impose on his 344-square-foot apartment, which he renovated last year. What appears to be an open-plan studio actually contains many rooms, because of sliding wall units, fold-down tables and chairs, and the habitual kinesis of a resident in a small space. As Mr. Chang put it, "I glide around."
Be sure to check out the photos if you follow the link through to the article.