I recently watched the Space Trek TED Talks on NETFLIX and here are my takeaways on our ability to find Aliens.
1. SETI is a joke. Well maybe that's harsh. I just think it's a long shot that we'll find Alien transmissions. Why? Because there's just too many assumptions we're making when we use our technology to find theirs. I appreciate the effort and we need to do it nevertheless I think it's unlikely to yield results.
2. Kepler is very promising. Kepler is searching for earth like planets orbiting stars. The science is straightforward and already finding lots of good prospects. It's only drawback is that it's only searching a small portion of the sky. Hopefully some day we can send many satellite Keplers to hunt out earth like planets orbiting stars. This technology still makes the assumption that if we can find an earth sized planet orbiting a star then we can find life but that assumption is a smaller leap then the assumption that Alien technology would be like ours… I mean we've all seen the movies... their technology is always superior!
3. Astronomical spectroscopy (non radio frequency). This is where we use non RF radiation from a planet to tell what the environment on the planet is like. Once we find suitable planets using Kelper, we could analyze those planets to see if the environment on those planets are earth like. If they are, then perhaps we could colonize the planet or better yet, find life on that planet.
These are exciting times we live in.