The latest news is that Saturn's Moon Titan also seems to have an liquid ocean under the crust of ice (ref1, ref2). But it's not the first such body to be discovered: Jupiter's satellites Callisto, Ganymede and Europa also have subsurface oceans. Additionally dwarf planet Ceres also has a large mantle of ice-water that may be as much as 60% of its total volume and that is more freshwater than can be found on Earth.
We are still trying to find out if there is water on (or rather in) Mars but in any case it seems that water is much more common than we first thought in our little stellar system. This offers lots of posibilities: first of all the potential of naturally existing life, even if of microbial type maybe, in some of these bodies - but also, long term thinking, it may be of help for space exploration, as water can be a source not only of the much needed liquid that makes up 70% of our bodies but also of oxygen to breath.