Cedric, silly question how are you calling markdown in your template?

According to the code it should be hyperlinking bare url's:

      def markdown(self, hyperlink=1):
        """ Render the value of the property as markdown.

            This requires markdown2 or markdown to be installed
            separately.
        """
 
Are you setting hyperlink to 0?

Also probably need to update the list to include mistune as well but...