The MRO Context camera team noticed a dark spot in an image taken in August 2010 that was not present in a Mars Odyssey THEMIS image taken in December 2007.
The team therefore requested a full-resolution HiRISE image of the dark spot to determine whether it was caused by an impact. Indeed, the HiRISE image shows an approximately 7 meter-diameter fresh crater and dark ejecta blanket at this location. These small impact craters continue to form on Mars, and are most easily recognized in areas covered by bright dust.
Written by: Ken Herkenhoff (6 October 2010)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_019195_2175
Image: NASA/JPL/University of Arizona