Getting busted for having an ounce or less of marijuana in California is no longer that big a deal, or even a crime, under a new law signed by Gov. Arnold Schwarzenegger. Instead of facing a misdemeanor charge, people caught will a small amount of marijuana will now get, at most, a $100 fine. With everything else on his plate — a big budget deal, a landmark health insurance exchange — what might have motivated Schwarzenegger to decriminalize marijuana now?