comma separated cck multivalues in a view
Per the following on drupal.org:
http://drupal.org/node/1018198#comment-3993646


  You can do this by copying "views-view-field.tpl.php" into your theme's directory, under 
  a name the view will recognize it selectively. Put the following code in it:
  
  
    print preg_replace('/&lt;\/div&gt;&lt;div[^&gt;]+&gt;/i', ', ', $output);
  


In your case, I think it would be:


  views-view-field--VIEWNAME--field_authors_value.tpl.php