This topic from Long and Short Reviews was interesting. I'd like to give a better answer than "don't know", so I gave it a decent amount of thought, but whether I came up with a good answer is open to question.
I dealt with aliens in my short "Watch the Skies", about a group of alien hunters whose lives are transformed when they end up encountering more than they bargained for. This was inspired by numerous paranormal shows I had watched on Really and Syfy, and came from the fact that - unsurprisingly - none of these shows ever find anything. They might see the odd light in the sky, but it's probably a plane or a planet.
My own thoughts? I think it's plausible that there is alien life out there, but much as I like the idea of a Star Trek Federation, I highly doubt I'm ever going to encounter one. It's probably for the best. I don't think any aliens would be remotely interested in me.
So do you believe in aliens?