They might not be able to control McCain and his occasional verbal wanderings, but the graduates of the Bush/Cheney campaigns know that surrogates can only say what they're allowed to say.
So when "senior McCain surrogate" Steve Forbes says on CNN that "cap and trade is going to go the way of some other things....I don’t think those things are going to get very far," that's because Forbes is being allowed to say it. Bush made similar promises and reversed them after getting elected. Now we're getting a warning.
(And I don't actually question that McCain vaguely wants some kind of greenhouse gas regulations, but I expect Bush actually believed what he was saying in 2000 too. The issue is what McCain would actually do, and it doesn't look good.)
UPDATE: Turns out that McCain policy adviser Nancy Pfotenhauer is from a dirty energy, privately held company (Koch Industries) and ran a climate denialist, astroturf group called Americans for Prosperity. Policy advisers are likely to transition from the campaign to the administration if McCain's elected, so people like her would be in charge of McCain's climate policy. Wonderful.