Oil fell by as much as $5 a barrel this week before rallying slightly, with the prices of gold, copper, wheat and rice also dipping. A pause for breath, many commodity market players say, after last week's heady highs. But others are posing the question: could oil at $135 a barrel have been the commodity boom's last hurrah?

Calling a peak to a market is a difficult task, and one most commodities analysts are loath to do with any precision. The task is particularly hard for commodities, an umbrella that covers base metals, precious metals, energy and food, all moving to their own dynamic.