The U.S. Department of Energy will be hosting the Solar Decathlon on the National Mall from Oct 9-13, 15-18, 2009. According to the website, "The Solar Decathlon joins 20 college and university teams in a competition to design, build, and operate the most attractive and energy-efficient solar-powered house."
I walked around this event the last time it was held in 2007 and the students from these universities are able to construct some pretty amazing sustainable houses in a very short period of time. Here is the link for the event:
http://www.solardecathlon.org/