I guess the main issue with this conversation is the term of "intelligent life". What makes life intelligent? Is it language? Killer whales have an incredibly complex system of communication with various dialects depending on the part of the world. I'm not saying that Killer Whales are even remotely close to human intelligence or that intelligent life would need to be even remotely similar to us humans. I do feel as though there is almost certainly a creature out there on one of the seemingly infinite number of planets that has language.
You bring up an interesting point though. "The Great Filter" ensures that the civilizaiton couldn't be too intelligent or far along in their history.