NASA has announced that the Mars Reconnaissance Orbiter snapped some interesting photos that seem to indicate that water still flows on the surface of the red planet during the summer months.
No water was directly detected but the presence of those long dark lines stretching from the slope suggest the a wet process is taking place. But, how does water flow in the sub-zero Martian temperatures? The dark lines are richer in ferric and ferrous materials than the surrounding area; Scientists at the Georgia Institute of Technology think that the iron-mineral compounds are a natural anti-freeze letting water flow during the warmest time of the Martian year.
A gif of the effect can be found here