By alexmoreno, 9 January, 2013

very simple:

        global $theme_key;

      echo $theme_key;

 

if we need more information, we can use this:

       $themes = list_themes();

       $theme_object = $themes[$theme_key];

 

        // print all the object fields

       var_dump($theme_object);

 

via http://drupal.org/node/46961#comment-88354