Are aliens all just hyper smart AI's? Have they been with us all along?
I am a huge of science fiction, and even have a record of 322 scifi novels I've read on this site. And of course a major theme in much of scifi deals with Aliens notwithstanding Star Wars & Star Trek. I'm a huge fan of Ian M. Banks and Peter F. Hamilton which built amazing universes populated by AIs and the like.
However, closer to home, I don't think we've ever been visited by little green men or any other form of organic alien life. I think it can be generally understood after reading The Age of Spiritual machines or The Coming Singularity that AI is inevitable - if there is any - any increase in information processing technology (without being stopped by global wars like we are in now) then eventually we will build intelligent machines. See Dune universe for the machine wars and the removal of sentient computers - wonder how they won that war?