Phoenix finds water on Mars! Was Mars once inhabited?

NASA's Pheonix Mars mission has analyzed a frozen soil sample collected on Mars and found traces of water:

"We have water," said William Boynton of the University of Arizona, lead scientist for the Thermal and Evolved-Gas Analyzer, or TEGA. "We've seen evidence for this water ice before in observations by the Mars Odyssey orbiter and in disappearing chunks observed by Phoenix last month, but this is the first time Martian water has been touched and tasted."(source)