Wordpress: Custom admin logo

gistfile1

//Custom admin logo - 30px wide, 31px high transparent gif. Header background color: #464646
add_action('admin_head', 'my_custom_logo');

function my_custom_logo() {
   echo '
      <style type="text/css">
         #header-logo { background-image: url('.get_bloginfo('template_directory').'/images/custom-logo.gif) !important; }
      </style>
   ';
}