This image is one of the very first sent home from Curiosity, showing the rover's own shadow on the Martian surface. NASA says that the clear dust cover is still on the camera, hence the dust seen around the edge of the fish-eye image. The photo was taken by one of the rover's front hazard-avoidance cameras on the vehicle's front end, at only one-quarter of full-resolution.
Larger color images should come later in the week when Curiosity's mast is deployed. The mast carries high-resolution cameras.