With ample reason, nonmembers have never been especially fond of OPEC, but no one would know it from the looks of the chummy gathering in Vienna last week. Suddenly oil-country diplomats who only a few years ago would have been mortified to be seen cooperating with OPEC were showing up and making conciliatory gestures. A Chinese official was there, chatting with his counterpart from Mexico during a photo session. An oil-patch emissary from Texas mingled on the sidelines with ministers from Malaysia and other countries. Even an observer from the petrol-pumping province of Alberta, Canada, joined the unique assemblage.
It was...