Actually, this is a gigantic point

A Small, But Important, Difference In The Candidates’ Cap-And-Trade Plans

Incidentally, while the public clamors for drill, drill, drill, Mr. Obama wants high-cost, cap-and-trade carbon regulation enforced by the Environmental Protection Agency. Now, Mr. McCain also wants cap-and-trade, but not if India and China don’t go along. Apparently Mr. Obama will not be constrained by the rest of the world.

I see no evidence that China or India will ever be stupid enough to buy into cap-and-trade. If we only do cap-and-trade if China and India go along, it almost certainly means that we won't do cap-and-trade at all.