Is there life out there?

Earlier this month astronomers announced that they are on the verge of discovering Earth-like planets orbiting other stars.
NASA's new Kepler telescope is discovering previously unknown planets on an almost daily basis. A high proportion of the trillions of stars now appear to be orbited by planets which we had been unable to detect previously. They are calling these 'exoplanets', to distinguish them from the planets within our own solar system. The sheer volume of these exoplanets suggests that sooner or later we will discover hundreds of planets that have the kind of surface and atmosphere and the right location in relation to its star to support life.
Some scientists claim that within the next few years they will discover a planet where all the conditions for life are present and where indeed life may already have developed...
These discoveries have led the Roman Catholic Church to hold scientific conferences about the prospect of finding extraterrestrial life, and the theological implications of this. In the press conference after such a Vatican conference last November, U.S. professor Chris Impey reflected on the implications of an encounter with an intelligent life form, saying, "If biology is not unique to the earth, or if life elsewhere differs bio-chemically from our version, or if we ever make contact with an intelligent species in the vastness of space, the implications for our self-image will be profound".
If the Vatican scientists are beginning to consider the issues for their faith of finding extra-terrestrial life, perhaps we should consider the implications for our own faith, rather than being left nonplussed if an announcement of such a discovery is made.
What would be the implications for Christianity of discovering life on another planet? Are there doctrines that would have to be amended? How would we react if intelligent life on another planet had its own form of religion? Or are we confident from what the Bible says that there is no possibility of intelligent life existing on other planets?

Wide Mercy
I am reminded of a verse from F.W. Faber’s hymn, “There’s a wideness in God’s mercy”:
“There is grace enough for thousands
Of new worlds as great as this;
There is room for fresh creations
In that upper home of bliss.”
It seems that in the middle of the 19th century, Faber had already tackled this question.
Who knows?
This kind of conversation always reminds me of Jesus, Peter and John on the lakeshore after the resurrection (Jn.21:15ff). Peter suddenly gets interested in what happens to John (21:21) - Jesus' response is "Never mind him - get on with your own job!"
I don't know whether or not there is life on other worlds. I suspect there is, and I half-suspect that when Jesus said "I have other sheep that are not of this sheep pen" (Jn.10:16) it contained a glance in that direction, although its primary meaning is more likely to be about the Gentiles who were coming to faith when John's Gospel was written. The point of Jesus' comment to Peter is that our discipleship is about where we are. That's where the rubber hits the road - it might be fun to speculate about the evangelistic outreach to Alpha Centauri (anyone for cafe church at the Restaurant at the End of the Universe?) but trying to discern evidence for ET in the Bible is just a waste of time and ingenuity.
Won't it be fun if the first little green man out of the flying saucer greets us "Shalom"? And won't it surprise a lot of folk if he says "Actually, where I come from, we're all Buddhists..."?
Only Humans Count?
If you think that the discovery of intelligent life on another planet will have no bearing on Christianity or Christian thinking, have a look at these Christian Answers to the question.