gistfile1.php

class Photograph extends DataObject {

   public static $db = array(
         'Feature' => 'Boolean'
   );

   public static $summary_fields = array(
         'Featured' => 'FeaturedReadable',
   );

   public static $casting = array(
      'FeaturedReadable' => 'Text'
   );

   public static function FeaturedReadable(){
      return $this->Feature ? 'Yes' : 'No';
   }