This quote in Sunday's Washington Post on Al Gore's Live Earth Concerts says just about everything.

John Buckley of Carbon Footprint, an organization that helps companies reduce their carbon dioxide emissions, said Saturday that Live Earth will produce about 74,500 tons of the gas.

"We would have to plant 100,000 trees to offset the effect of Live Earth," he said, speaking by telephone. But, he added, "if you can reach 2 billion people and raise awareness, that's pretty fantastic."

Like the headline says, it's the thought that counts. Any standards can be waived, no price is too high, as long as your motives are pure. Conversely, nothing you do (like tightening rules on diesel emissions) can earn you even medium-term goodwill if your motives are perceived to be impure.