"NASA's Mars Curiosity rover has measured a tenfold spike in methane, an organic chemical, in the atmosphere around it and detected other organic molecules in a rock-powder sample collected by the robotic laboratory's drill. "This temporary increase in methane -- sharply up and then back down -- tells us there must be some relatively localized source," said Sushil Atreya of the University of Michigan, Ann Arbor, and Curiosity rover science team. "There are many possible sources, biological or non-biological, such as interaction of water and rock."
Keith's 31 July 2014 update: I obviously expected Jim Green to answer in the same cautious way that NASA has always answered this question - one I have asked again and again for the nearly 20 years. Instead, Green launched into a detailed description of all the things that the Mars 2020 rover could detect that have a connection with life. Much of what he said clearly referred to extant / existing life. Now THAT is cool. To clarify things I sent the following request to NASA PAO "Can the Mars 2020 rover detect extant/existing life on Mars? Will NASA be looking for extant/existing life on Mars?" Let's see how they respond.
Keith's 16 Dec 2014 update: NASA SMD's Jim Green and NASA SMD PAO Dwayne Brown still refuse to respond to my original inquiry from July 2014.