I had just read one of Paul Krugman's latest blog entries and then read Evolution News and Views latest entry and was surprised at their apparent agreement about the open-mindedness of liberals and closed-mindedness of conservatives.
No doubt, if we asked ENV if they felt this was a truth that could be generalized to all issues, they would disagree and offer plenty of data that suggests that liberals can be just as closed-minded regarding other issues.
My own view is that most people, including yours truly, have difficulty listening to views with which we disagree. I don't think it matters much whether we are conservative or liberal. We all want to think we are right about most topics and shy away from anyone who might threaten that self-image.
UPDATE: I guess I should add that in my case, since most of my views are obviously true, there is no need for me to read the views of those who disagree with me. ;)