NASA reports that the Phoenix Mars Lander has stopped communicating as it has run out of power. As anticipated, seasonal decline in sunshine at the robot's arctic landing site is not providing enough sunlight for the solar arrays to collect the power necessary to charge batteries that operate the lander's instruments.

NASA will be listening carefully during the next few weeks to hear if Phoenix revives and phones home again. Launched Aug. 4, 2007, Phoenix landed May 25, 2008, farther north than any previous spacecraft to land on the Martian surface.
Phoenix verified the presence of water-ice in the Martian subsurface, which NASA's Mars Odyssey orbiter first detected remotely in 2002.
It is still an open question if there is/was life on Mars.
More details in this NASA announcement.