If you don't know what the Drake equation is, it's an equation made by Frank Drake that tells how many advanced civilizations there are in the galaxy. Scientist can't figure out what the variables are so you can decide with this website, it's pretty cool.

http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html

While I think life outside our solar system is highly probable, I tend to believe many people have the tendency to overestimate "fi" in the Drake equation. Many seem to think we are so "evolved", so perfect that life MUST have lead to a similar form of life. IMO, saying "intelligence is such a survival advantage that it will certainly evolve" is extremely arrogant.

 

My guestimate; 0.001

IMO, saying "intelligence is such a survival advantage that it will certainly evolve" is extremely arrogant.

 

While you are probably right in assuming that there are other features that an organism could evolve to make it as adaptable to a rapidly changing environment as intelligence, it is still a significant one. Thus the likelihood of it manifesting itself in any long populated ecology would be high. Your statement seems to subsume the now discredited belief that Man (because he is intelligent) is the at apex of evolution.