Honestly, I've come to disagree with the "paradox". The ability to send physical evidence of other intelligent life is based on a certain speed limit of the universe. So that doesn't serve as much of a lack of evidence. Habitable planets are too far apart for much interstellar travel to occur readily given that the speed limit is c.

Beyond that, the power of a radio signal is inversely proportional to the square of the distance, and we have things like magnetic eddies at the edge of our heliosphere, so it might just be incredibly improbable for any civilization to have generated the types of signal creation that we would pick up.

In the hypothetical/fantastical, other advanced civilizations might have long distance, superluminal communication technology, but that's not something our civilization could actively intercept.

tldr; I don't buy Fermi's paradox.

The Fermi paradox is "why a highly developed civilization isn't behaving like a Western colonialists or tourists toward primitive natives of some remote wilderness".

As far as we understand physics, actually traveling through interstellar medium is very very slow. Light itself takes next to forever to go from here to there. Most likely, intelligent species realized it was much more fun to explore inner space rather than outer space. I'd wager we won't see them: they've surrounded their local stars with Dyson Spheres, communicating with highly directed, encrypted, massively wide-band, low power communications that would look rather like background radiation unless they were pointed right at us and we were meters away.

Think about how important latency is to high frequency traders. In an information ecosystem, the laws of physics become paramount: latency and bandwidth are king. Physically being far from the action is essentially choosing to banish yourself to the hinterlands when everything exciting/valuable is happening at the hot core as close to the ball of fusion in the middle.

update: Thinking further, if anyone has in fact developed FTL, you can bet your ass they don't want anyone else to have it. In space, Sir Isaac Newton is the deadliest MotherF&@$%^# around. A baseball going 99% C is a weapon of mass destruction (http://what-if.xkcd.com/1/), much less a ship, which would essentially be a planet destroyer you literally couldn't see coming.

Yup.

I'm pretty sure we're screwed and interstellar colonization is impossible. At best, we'll get a probe that takes a thousand years to tell us what it found, and we'll only explore a handful of neighbouring systems this way before something eventually scrapes humanity down the memory hole.

Perhaps most (all?) advanced civilizations annihilate themselves (or get annihilated) before they have a chance to colonize other worlds?