And this is good context:
The debate over speculators underscores the shifting nature of commodities trading in recent years. Before the mid-1990s, these markets were dominated by entities that had physical dealings with the underlying commodity, and “speculators” who often took the opposite position, providing liquidity to markets.
But a new group of investors has emerged in recent years. Those who want to bet on commodities prices have increasingly put their money in indexes that track the value of futures contracts, in which investors promise to pay a certain amount in the future for oil and other commodities. As of July 2008, financial investors had about $300 billion riding on these indexes, roughly four times the level in January 2006, according to the International Energy Agency, a Paris-based watchdog.
Watch out for this story. It could get nasty.