Everyone I know in the low energy game (e.g. the directors of www.aecb.net) think it's a load of b*llocks. As far as they're concerned do anything and everything you can to reduce demand. They're equally scathing about grey water/rain water recycling, reduce demand first, then worry about anything else.

I've just had a hunt but couldn't find any relevant threads on their forum:

http://www.aecb.net/forum/index.php

Sign up, as a member you'll get a free sub to Green Building magazine which is really interesting.