Certain considerations suggest that the odds of finding a contemporary alien technological civilization in our galaxy are less than we might think. Far from being typical, our solar system may be a very special place:
Only a fraction of star systems are "friendly" to life as we know it. Blue/white giants burn out much too quickly for life to become established on any orbiting planets. Altair, for example, would be a poor prospect, despite its being the (fictional) home of the Krell in the film "Forbidden Planet." Red dwarfs, which I understand are much more abundant than Sol-like stars, have such a narrow "habitable zone" that planets are unlikely to remain within it year-round. Most stars are part of multiple-star systems, most of which will have no habitable zone whatsoever. Planets orbiting single stars that are more variable than our sun may suffer extreme climate variations that make even primitive life unsustainable.
It's been suggested in recent years that Jupiter and Saturn are exactly the right size in exactly the right orbits to sweep up space debris that would otherwise cause much more frequent mass extinctions on Earth.
Planets with more axial tilt than the Earth may suffer yearly climate variations too extreme for "higher" life forms to develop. Supposedly our unusually large (relative to its primary) moon helps stabilize the Earth's axis.
Speaking of the moon, I recall a Larry Niven story based on the premise that the moon facilitated life on Earth by sucking off some of our dense early atmosphere, which otherwise would have made the planet a "greenhouse" similar to Venus. I can't vouch for the scientific validity of this concept. I also recall an article by (I believe) Isaac Asimov in which he suggested that tide pools (the moon again) may have acted as a crucial transition zone in the evolution of air-breathing animals.
Our galaxy may have a "habitable zone" analogous to the zone around a star. Too close to the galactic center, and an otherwise habitable planet may be periodically sterilized by supernovas, radiation bursts, etc. from the relatively dense population of nearby stars or the black hole at galactic center. Too far from the center, and the abundance of "metals" (elements with atomic number above 2) may be too low to produce stellar systems with such life-essential elements as carbon, nitrogen, and oxygen. Depending on the width of this zone, the vast majority of our galaxy's stellar systems may be unsuitable for life on this basis alone.
Life apparently developed on Earth as early as 3.5 to 4 billion years ago, but remained "primitive" until about half a billion years ago. This suggests that under the right conditions the odds of developing life are high, but development of "higher" life forms is much less likely. This idea was used in the film "Mission to Mars", which explained the so-called "Cambrian explosion" of complex life forms as alien seeding.
Some of these ideas (and others) are discussed at
http://www.spacedaily.com/news/life-00z1.html
Re: OT: Extrasolar planets discovered directly
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