But didn't you read this...
And the number of intelligent civilizations in our galaxy is… 31573.52
See here:
http://arxivblog.com/?p=674
And in a week or two I am sure we will see another news item about
how plentiful planets are in the Milky Way and that they have plenty
of time and materials to develop into full life-bearing worlds.
It is great that we are far enough along in our knowledge in this area
to actually have some data points, but we really need to get some of
those big telescopes up in space that can actually image alien planets,
or we'll just keep guessing back and forth forever.