When this issue is raised, it makes me wonder how absurd our idea of "intelligent life" might be. We assume that we're intelligent because we're self aware and we use tools and we build stuff, right? But the "self aware" thing is arguable. How self-aware are we on the self-awareness spectrum? Our senses are pretty limited. Our grasp of the physical universe is nascent. Our scope of observation is laughable, right? So what frame of reference do we have to work with in terms of looking for intelligent life? Seems like if we're talking about life as intelligent as we are at our current juncture, the chances are pretty slim even if several million such peoples populate other planets. Problem being, we're not quite intelligent enough. So are we talking about beings more intelligent than us? Well, if they're substantially more intelligent, then would they allow themselves to be noticed, or would they have recognized that as a bad idea? And if they allowed themselves to be noticed, would we even recognize them as intelligent? Would we recognize them as beings? Or would it be like a beetle trying to conceptualize an octopus within the rubric of "beetle-ness?"

I suppose eventually (or, what, immediately?) we'll have advanced enough observational tech to at least recognize the planets best suited for our specific style of organic intelligent life. From there, though, it's still a far cry from actually discovering that life within the right time frame with limited technologies.