Though, if there is one area in which any state could claim some justification for signing treaties with foreign powers, it might be air pollution and California. After all, the federal government, via the Clean Air Act, has given California nearly co-equal status. The EPA sets emissions standards for various kinds of engines, including cars. The states are preempted from having their own standards--except California, which can set standards different from the EPA's. And all the other states can choose to follow either the EPA or California.
But, still, the Bushies have to see this as an insult from Arnold S., and Tony B. may not be their favorite