public static string News_Pic(DateTime T)
           {
               if   (T.Date   ==   DateTime.Now.Date)
                {
                    return   \"Images/New.gif\";   ;
                    }
                     else
               {
               return   \"Images/No.gif\";
             }
                 }

    前台页面调用

    模板里调用<img src=\"<%#Common.News_Pic(Convert.ToDateTime(Eval(\"AddDate\")))%>\" width=\"22\" height=\"9\" />