Hi Res version - 1.5 mb Jpg

ESA Mars Express picture - water on Mars?
The blue color might be a false color effect, but there's no explanation for it in the link above. Or could it actually be real life water on the Martian surface?
UPDATE
In this Space.com article,Gerhard Neukum of Germany's Free University of Berlin said it is too early to determine the composition of the black-colored substance at the bottom of the now dry river beds.

Hang on a minute - those blotches to the left are certainly blue in color, not black. Later on in the space.com article, Neukum confirms that what we are looking at is real and not colourised:
"Neukum also said the colors of the images produced by the stereo camera is as realistic as possible and are not enhanced to provide additional details. "What you are seeing is real," he said."

In the hi-res version of the image,you can see the blue areas more clearly.Frozen water maybe? Or actual flowing water gushing out because of previously undiscovered underground volcanic activity??

Note the channels flowing into the blue "lake" in the rough middle of the image. Strange isn't it? Remember that the common scientific consensus is that flowing water shouldn't exist on Mars - although that is changing. Under ground heat from periodic vulcanism could create very brief mini-floods of water bursting to the surface for example. The water wouldn't stay around , due to Mars' very thin athmosphere, but it suggests that possibly Mars' water hasn't evaporated away , but is locked in some kind of super-hard permafrost , just below the surface.

And if that is really the case, then the case for a manned mission going to Mars is even more compelling.