New Scientist is reporting the Mars rover Spirit may already be seeing signs of water before it even moves off its landing pad:

The first images taken by the craft's mini-Thermal Emission Spectrometer - an infrared instrument capable of indicating the composition of nearby soils and rocks - show evidence of carbonates and hydrated minerals. Both of these are usually, though not exclusively, produced in long-standing bodies of water.

The sooner this thing gets moving, the sooner we find out!