Scienceblogger, biologist, gadfly, and Minnesotan PZ Myers writes about why extraterrestrial intelligence is unlikely. In brief, it's because intelligence is just one of many evolutionary traits, and an exceedingly rare one at that.
I love reading Myers' main blog, Pharyngula, because he's a great writer, an excellent expositor of scientific knowledge, and an unabashed liberal - and atheist. This anti-ET post is par for the course: in clear, non-technical language, he clearly applies evolutionary theory to a fascinating scientific problem - whether life exists Out There - and comes to a thoroughly scientific conclusion.