Allegations that traders manipulated oil prices in 2008 are reinforcing the buzz — at the gas pump and elsewhere — that speculators are driving up the price of oil, triggering wild price spikes and nail-biting volatility. In a federal lawsuit filed on May 24, the Commodity Futures Trading Commission (CFTC) charged two traders from a Swiss firm with hoarding and dumping millions of barrels of oil to reap more than million on derivatives contracts. The allegations come three weeks after President Barack Obama appointed a task force to investigate oil price fraud and manipulation, and just one day after the Democratic staff of a House oversight committee reported that “excessive oil speculation could be inflating prices by up to 30%.”    Fingering speculators is a popular pastime these days, but experts at Wharton and elsewhere say the blame is often misplaced.…