Is intelligent extraterrestrial life out there somewhere?

Define "intelligent" and then use that scheme to classify all known terrestrial organisms. It's the best we can do for now, unfortunately.

Technologically-advanced extraterrestrial civilizations could be so alien that they don't even pique our interest. Evidence of alien civilizations, particularly when we are forced to contend with profound differences in biology, may not be recognizable to us as the products of "life" at all. If intelligent extraterrestrials happen to be highly skilled in areas such as conservation and the reduction/minimization of environmental footprints, they could simply blend into the background and we would be none the wiser. Unless their civilizations are sufficiently similar (in their evolutionary paths and biology) to our own, we could miss each other completely... passing like two dark ships in the night.

I think a better question is, "What are the odds that we will find an extraterrestrial civilization enough like us that we will be able to recognize each other?" The galaxy could be teeming with technologies beyond our wildest dreams but if we lack the means with which to detect them (and signal the presence of our own existence), we may (wrongfully) come to believe that we are alone in the universe.