Last season in Antarctica, we focused on trying to understand "water tracks"--small meltwater channels that percolate downslope through Antarctic permafrost (frozen soil). The idea is that snow and ground ice melt in the summer, and the water flows downhill under the pull of gravity. Because there's not a lot of water, it just oozes through the soil, rather than flowing atop the soil as a stream. As a result, water tracks show up as lines of wet soil snaking down valley walls in the Antarctic landscape.
Now it seems that water tracks may have been discovered on Mars by Alfred McEwen and the HiRISE camera team. For full coverage see BBC and Science.