http://www.space.com/scienceastronomy/080320-mars-salt-deposits.html

also relevant is

http://www.space.com/searchforlife/080320-seti-mars-water.html

My own take - I think there's a bit of spin and hype coming back into discussion of past water on Mars. We're back to the search for life (and intelligent life at that!). Frankly, I think it's unrealistic. let's understand the history of this cold dry planet, and not try to impose our hopes and wishes on it...