Rastogi's back-of-the-envelope calculation on the carbon issue seems basically right to me, but suggesting that the government was valuing the carbon, alone, at the full cost of the program, is just silly. A lot of what they're interested in buying is stimulus to Aggregate Demand. And the industry numbers suggest that they did pretty well on that front. I might argue that they'd do better, in the long run, both for the economy and the environment, by investing more in making cars less necessary in more places, by providing incentives and grants for communities to densify and improve public transit. But comparing the program to direct carbon offset purchases, without thinking about the larger economic context, seems silly.

Plus, reducing gasoline/oil usage has more than just an environmental motivation - think of the lengths we've gone to to stay cozy with other oil-producing nations. auros is right; valuing the carbon alone is a little silly...