Water On Mars?

[PAW]

Today (12/06/06) they announced that they think they've found definitive evidence of liquid water on Mars.
Since the boiling point of water is a function of pressure, and since, as I understand it, the atmospheric pressure on Mars is about 90 times less than that on Earth, if any volcanic activity on Mars produced water wouldn't that water immediately boil into a vapor?
And, further, wouldn't any ice that forms from that vapor at that pressure almost immediately sublime back into vapor?

Patrick
Santa Cruz