The possibility of
life outside of our own solar system is possible, but due to our own system being a bit of a
lucky fluke it is unlikely that each
star system, or even most star systems, contain intelligent life.
Our solar system contains a gas giant (Jupiter) in the outer system and the third planet's (Earth) moon is proportionally larger than most planet's moons. Jupiter manages to reel in any large rogue asteriods and keep them in an orbit between mars and itself or deflect them back out into space, protecting the inner planets from any serious damage (although Hollywood will probably continue to make large-death-asteriod-movies). Earth's moon serves to keep our planet upright. If the moon was smaller or didn't exist, Earth would flip its axis every 100,000 years or so. That means that what was once a point on the equator would become the north pole, and any life that had developed in that time would most likely perish in the new environment. Hence, no time for evolution and no intelligent life.