I've just done a Slate piece elaborating on what would happen if a hurricane hit the Gulf oil slick, based upon further research and interviewing. Here's an excerpt:
Much depends on the angle at which the storm crosses the slick. In the Northern Hemisphere, hurricanes rotate counterclockwise, with the largest storm surge occurring where the winds blow in the direction the storm as a whole is traveling—that's in front of the eye and off to the right. (Meteorologists worry over a hurricane's dangerous "right-front quadrant.") So if a powerful storm approached the slick from the southwest, say, its most potent winds would push the oil forward, instead of sweeping it off to the side and out of the storm's path. If the storm then plowed into the Gulf Coast, you'd expect an oily landfall. And how would the slick affect the storm? Not much if at all:
...by the time winds reach hurricane force (greater than 74 mph), they cause so much ocean mixing that any oil slick on the surface would be driven down into the depths and generally broken up. MIT hurricane expert Kerry Emanuel has tested the phenomenon on a small scale using an enclosed tank, half filled with water, ...