The Phoenix Mars Lander photographed a series of dust devils on Sept. 9. The start of a video sequence can be seen in the upper left of the photo. Follow the link below to see it move across the landscape.
According to the project Web site:
"The dust devil visible in this sequence was about 1,000 meters (about 3,300 feet) from the lander when the first frame was taken, and had moved to about 1,700 meters (about 5,600 feet) away by the time the last frame was taken about two and a half minutes later. The dust devil was moving westward at an estimated speed of 5 meters per second (11 miles per hour), which is similar to typical late-morning wind speed and direction indicated by the telltale wind gauge on Phoenix. This dust devil is about 5 meters (16 feet) in diameter. This is much smaller than dust devils that have been observed by NASA's Mars Exploration Rover Spirit much closer to the equator."