The NASA scientists working with the Phoenix lander have made a significant announcement today in confirming that ice is just under the surface at Mars' polar regions. The photo above shows a white area that is clearly changing over four days. Another section of the photo shows several pebbles disappearing - a sign interpreted as melting ice.
This is exciting for a couple of reasons. First is that it raises the prospects of finding life on Mars. Not the Hollywood LGM but something on a microscopic level seems more plausible now that we have found water (especially considering how quickly and pervasive it appears to be at the Phoenix touchdown site).
Second, it improves the odds of eventually having human explorers there. If water is present then an expedition team can use that as a resource (it is a big benefit not having to take water with you). It sparks the imagination of what humanity might achieve later in this century towards creating an outpost.
Of course it's a big question whether the U.S. will be spearheading any such effort. China at this point seems far more focused on accessing space and potentially controlling it, as well as having the financial resources to fund it. But no matter who arrives there one thing is for sure - this discovery will serve as a significant cornerstone on that day.