I'd still go for fixing it. The link describes a conversation with Microsoft about its continued role in the Chamber, despite Microsoft's opposition to the Chamber's policy. Corporations like Microsoft might be willing to work for change, but I don't think they'd be willing to quit. Also, green businesses could change local and state level Chambers even before they affect the national level, so it's not an all-or-nothing quest.
Other interesting news: Warming Law discusses the nuisance case against greenhouse gas polluters that has just passed an important hurdle of being accepted at the appellate level. It's possible that the Supreme Court will kill it, but I wouldn't count on it. Good news, and one more bargaining chip to help push the polluters in the right direction.