Vision for a visualizaton:
Dark blue background, potentially speckled with stars. First line, large white font, may even resemble the Star Wars font says, “ARE WE ALONE?”
The middle of the poster might have a diagram of the Kepler satellite, potentially some pictures of the planets or our solar system all lined up by size. Basically there will be some kind of visualization, maybe even just a pie chart, of what proportion of planets Kepler finds that are Earth sized (super-Earths not included). Then an estimate of how many planets there are in the Milky Way, then some simple math to show how many of those would be Earth sized. Then there might be a discussion of how many of those planets are in the habitable zone. And finally a discussion of the probability of an Earth-sized planet in the habitable zone having an appropriate atmosphere. All of this data would ultimately lead to a number that would either be the number of such planets in the Milky Way, or the probability of a given planet being able to support life. Because those numbers are interesting.
Near the bottom (depending on the result) it would say something like, “MAYBE.” or “PROBABLY NOT.” or “YES.”
And then below that there would be a few further questions. I am personally interested in the probability that any life found would be more or less evolved than us. Is Earth a relatively young or old planet? Would evolution take place at a similar place on other planets? And if some data could be found on those questions another (that non-scientists especially might like) is: If we found life less evolved than ourselves, should we try to influence it?