A news item published today on the website of the journal Science reports the discovery of dark seasonal streaks that appear on some equator-facing slopes on Mars when the local temperature rises high enough.
Here are the last two paragraphs of the article, the last one being particularly interesting:
"This may be our best evidence yet of liquid water emerging on the surface of Mars," says planetary scientist Oded Aharonson of the California Institute of Technology in Pasadena. Flowing water is not yet proven, he says, but "I would bet my bike on this, and probably my car, but I wouldn't bet my house on it."
"It's exciting," says planetary scientist Joseph Levy of Portland State University in Oregon. "Mars looks more like the Dry Valleys of Antarctica every day." That's the largely ice-free part of the continent where trickles of summertime meltwater can dampen slopes and support a hardscrabble microbial population, including algae, just beneath the surface. A damp subsurface is where life is most likely to be found today on Mars, notes McEwen. "Now we see perhaps some groundwater is coming to the surface. It gives us a location to focus on" as NASA continues to "follow the water" in search of martian life, past or present.
There's another article here from The Washington Post.