The WSJ has a good update on what's going on with the price differential between WTI and Brent. For example: "Though Brent and WTI represent two similar types of oil, they are subject to different regional forces. Before the start of the year, Cushing already was facing price pressures caused by a glut of oil. At the same time, Brent crude, the European benchmark, was buffeted by supply disruptions due to unrest in the Middle East. When the uprising against Moammar Gadhafi caused oil production to grind to a halt, Brent crude prices rose."