Back to my regularly scheduled programming..
A friend pointed this out, saying, Put your money where your mouth is, choose your oil suppliers wisely, dollars work faster than votes, and are more dependable than regulations.
It's also interesting data, some which I'd been looking for anyway. Further, it makes the "We won't go for Texaco" chants, while catchy, pretty silly.
[edit: please see the comments for a revised link]