In contrast to all the other endeavors these guys have cooked up (at least in terms of pimping themselves on their own sites), mega-engine Yahoo! has finally moved their environmental foray, Yahoo! Green, from the beta-stage to the prime time with very little fanfare.
There's not too much that one might call new in the Green features--there's a dedicated columnist and a counter of carbon savings--but for the most part the site is a portal that provides other Yahoo! content in aggregate (news, Yahoo! Answers, chat).
Still, lots of good info here and you don't have to look around. Besides, if you have to have an aggregate, better this than Yahoo! Kitten Punching. Or, and I'm not kidding, the other new product they're working on.