Apologies to Pete Seeger, but last Monday, when I checked in at registration for Fortune's annual Brainstorm Green conference and was handed the magazine's latest issue, I didn't expect the cover to be grey with an image of an unnerved executive, chair blasting into space (at least I hope that's what the picture is supposed to be, the delinquent in me has other ideas). Yes, there was a story about "The Truth About Green," but it wasn't the cover story.

I walked up to the gift shop to peruse the magazine rack. My search eventually took me to several newsstands and book stores. The most I could find a week before Earth Day was a green issue of Scientific American and a Harvard Business Review special issue rolling up articles from their past. The only other significant feature I had seen was last week's New York Times Magazine cover story by Paul Krugman on "Building a Green Economy," but then anyone employing Tom Friedman is likely obligated to feature at least one green story in the run-up to Earth week.

Alas, will there be no one to follow Vanity Fair's green cover trail after Madonna and Julia and Leonardo?

I've lost count of the number of presentations I've seen that used magazine covers on top of magazine covers to validate the importance of environmental sustainability. In my cursory search last week, it seems the covers are gone. And at an event like Brainstorm Green, it seems the cheerleading has been replaced by an engaged, if some times nuanced, discussion.

BSG without PPT

Fortune's Brainstorm Green brings together senior executives from across a wide range of industries along with leaders of non-governmental organizations, a few high-profile consultants, representatives of the investment community, and others. The event is a collection of main stage one -- on-one interviews, panel discussions, and numerous breakout sessions.

Suffice to say that the conversations, both on stage and in the hallways, are some of the best I get to participate in all year. Part of the reason for that is they highlight the challenges facing business in dealing with the environment and climate change. But there's also a candid openness to the event that is encouraging when you're interacting with Fortune 500 executives whose investor relations departments often try to tamp down the chief's enthusiasm.

Lee Scott, former CEO of Walmart, kicked off the event with a wide-ranging discussion during which he cleared up something I'd always been curious about. Namely, when Walmart set its emissions reduction, waste, and other sustainability goals there was no time frame attached to them. Environmentalists criticized that but his explanation is a great example of the challenges of leading any sizable organization. Consensus was dragged down by individual interests and meetings turned into negotiating sessions about what the exact goals might be. To his credit, Lee took a stand to publish bold goals and figure out the timetable later. It might not have been a popular decision, but it's the type of decision many leaders shy away from, delegating their responsibility.