New Scientist is carrying this update on current goings-on with the Mars rovers. Includes this very weird revelation:
Opportunity is taking advantage of a mysterious power boost, which is still baffling scientists at NASA's Jet Propulsion Laboratory in Pasadena, California. Something seems to pass by at night and sweep dust from the rover's solar panels, allowing them to absorb more sunlight the next day.
Cue "X-Files" theme song!