You probably already heard that despite divers problems, the Phoenix Mars lander finally managed to prove the existence of water (ice) in Mars soil (better told in the 'regolith'). Well, there was already before sufficient evidence available for both present ice, and even past flowing water, but this was the first time water was touched and sensed. See for example here for more details:
"We Have Water" on Mars, TEGA Test Confirms | Universe Today
However, now it looks like NASA may have some important information about the presence of life on Mars. Let's hope it won't stay behind the locks for too long time as it already happened in the past - for example in 1996 with the announcement regarding the “Mars rock” -
ALH84001 - when AAAS/Science magazine tried to keep it all under embargo, or in 1976 at the Viking lander, where possible signs of life were precipitately blamed on contamination from Earth (
SPACE.com -- Scientists Say Mars Viking Mission Found Life)
More details about the current expected announcement here:
The White House is Briefed: Phoenix About to Announce "Potential For Life" on Mars | Universe Today
or here:
LiveScience.com Blogs » Blog Archive » Phoenix on Mars Life - Message From MECA