Update: Ice on Mars!

From Wired:

There is water ice on Mars within reach of the Mars Phoenix Lander, NASA scientists announced Thursday.

Photographic evidence settles the debate over the nature of the white material seen in photographs sent back by the craft. As seen in lower left of this image, chunks of the ice sublimed (changed directly from solid to gas) over the course of four days, after the lander's digging exposed them.

"It must be ice," said the Phoenix Lander's lead investigator, Peter Smith. "These little clumps completely disappearing over the course of a few days, that is perfect evidence that it's ice."