A study was just published in the Proceedings of the National Academy of Science, in which astronomers calculate that at least 8.8 billion stars have planets the size of Earth, with habitable temperatures. http://news.yahoo.com/study-8-8-billion-earth-size-just-planets-212232920.html
These kinds of stories always raise enjoyable, speculative questions. If these hypothetical worlds are habitable, what kind of life do they have? Carbon-based? Self-conscious?
If capable of philosophical reflection, do they wonder who else is "out there"? Do they bring about the extinction of other life forms, as we humans do here on earth?
If capable of theological reflection, what is their conception of God, and would it dovetail with religions on earth? Or, like us, do they have several religions systems?
How do they think God has made Godself known? Do they have religions sagas, epics, and law codes from earlier times that guide their everyday lives?
What, if any, is their technological development? A typical fiction is that, if other life forms are capable of distorting spacetime in order to achieve faster-than-light travel (or if they are capable of discovering and utilizing traversable wormholes), they would be advanced enough to exploit us.
What if the religious ideas from these other worlds were such that the life forms want us to believe as they do, and when they arrive, they have a theology that they seek for us to embrace (through preaching or dissemination of information)?
All these questions are moot, of course, if other life forms are still in the stages of, for instance, our earth's Proterozoic eon. Things will be just getting started.