After installing WordPress 1.5 (like it very much) I realized that it nofollows every comments by default. Also it does it for the url link for comment author. I think this should be a choice. Hence I wrote a small plugin to provide an option to disable it (by activating the plugin).
The plugin has been tested only for WordPress 1.5 and is meant for 1.5 and beyond (till WordPress authors provide it as an option).
The details along with download link is at: http://blog.taragana.com/index.php/archive/wordpress-15-plugin-strip-nofollow-tag-from-comment-urls/