New computer modeling suggests that every rocky world like Earth will sport an ocean of water early on its history. That's because such woulds are built by smaller bodies sticking together, and those bodies generally have high water content. Later cometary impacts could also bring water, but the model does not require that water to have oceans.
This is clearly good news for those hunting alien life. Of course, oceans can be lost, as in the cases of both Venus and Mars. On the other hand, both Jupiter's large moon Europa and Saturn's small moon Enceladus-- neither of which is a rocky world in Earth's mold-- seem to have oceans that could possibly support life. Every step forward in our understanding of the universe seems to strengthen the case that life is abundant throughout the cosmos.