Speculation in the futures market is not the ONLY cause of high prices, but it is one of the factors driving the price up. The primary rise in prices has been the negligence in both the White House and in Congress on energy policy.
The DC Oil Barons are worse then even the OPEC Oil Barons. Perhaps citizens should sue the US Government for price gouging. Or perhaps an anticompetitive lawsuit is in order. The US Congress and Presidency control access to vast amounts of oil and they are restricting access to this oil and are partly responsible for the high prices and price gouging (simple Supply and Demand physics). And through Royalties, the US government is by far one of the highest percentage profiteers in the leasing of producing US oil resources.
Speculation has, as we have been learning to our great detriment, driven housing prices to very high levels, and a lot of folks who thought they had no choice if they wanted a house are stuck with bankruptcy as a consequence.
Speculators can have very very strong influences on markets. If you really need a barel of oil, and supply is inelastic, then a well healed speculator can make you pay well above the marginal cost of producing that barrel of oil.