Really Deep Waters: Life in the Solar System
It seems that the hottest prospects for extraterrestrial life in the solar system may be two icy moons, Jupiter's Europa and Saturn's Enceladus. Both appear to be covered by an icy surface that seems to recycle itself fairly frequently. Both appear to be heated by tidal forces due to their gas giant mother planets and other moons. It's at least plausible that there is an ocean of liquid water under all that ice.
Enceladus made a big push for the number one spot by spouting some vapor plumes near its South Pole. The Cassini probe was able to fly through the plume and measure water vapor, carbon compounds and other cool and suggestive stuff. Of course Cassini wasn't actually designed for that kind of work so the most fascinating organic clues lie beyond our reach - for now.
Europa is a bit larger than Earth's Moon, but Enceladus is tiny, only 500 or so in diameter.