"Plastics."
Not housing, but innovative nonetheless.
A biodegradable cell phone case that contains a seed that germinates once it's recycled.

http://www.engadget.com/entry/1234000257021952/
A plastic that's 90% cornstarch, and which completely disperses after adding water.

http://www.engadget.com/entry/1234000257021952/
http://asia.news.yahoo.com/051002/kyodo/d8d072eg0.html