This is actually a remarkably difficult thing for many businesses to get - or at least that's what it seems. How often do you see an ad which you know is stretching the truth to its limits. All those adverts for face creams which will "roll back the years", beer that makes you a more fun person, banks who are your best friend for live and animals playing drums!
Seriously, waste and getting the messages wrong are obviously bad. Getting the messages right and catching the mood is valuable. Environmental issues are something that many in the west now feel strongly about. If you can honestly incorporate these issues into your proposition (not just advertising material but what you actually do as an organisation) then aren't you more likely to catch the mood of a broad part of the public? Just don't go making false or exaggerated claims....
The marketing industry prides itself on taking a lead in consumer trends but for my part, I don't think it's done what it can as yet in this area. For many, the realisation that green issues are not just morally important but financially also appears to be taking some time to sink in.
For more on marketing and environmental issues, see an article by Nigel Hollis at Milward Brown -> http://www.mb-blog.com/index.php/2007/08/10/green-bubbles-pop-too-i-hope-not/
P.S. All ad revenues from this site today go to an environmental charity. Since a typical days ad revenues are normally pennies (I have canny readers who can't be influenced you see), you may wish to reconsider you usual browsing behaviour.