How Do The Various Web-Forum Engines Compare?

psyklohps asks: "I work at a local newspaper in Dover, DE. My boss is trying to setup a forum based site that will cover local news and get responses form the community. Unfortunately bosses are not very smart, and he is trying to develop the site from scratch. So I feel that I should tell him about the forum-based-code engines that are free. Of course my first choice would be Slashcode, but after looking on Google I found alot of different engines. PHPNuke, Zope, Squish.dot, and others that I have forgotten are available. What are the pros and cons for each of them?"