? gravatar.patch
Index: gravatar.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/gravatar/gravatar.module,v
retrieving revision 1.16.2.3
diff -u -p -r1.16.2.3 gravatar.module
--- gravatar.module	20 Jan 2011 16:18:39 -0000	1.16.2.3
+++ gravatar.module	22 Jan 2011 18:11:31 -0000
@@ -177,7 +177,7 @@ function _gravatar_get_account_user_pict
     // disabled for their account, use the global default image.
     return variable_get('user_picture_default', '');
   }
-  else {
+  elseif (!empty($account->mail)) {
     // Otherwise, show a gravatar with the appropraite default picture.
     $mail = $account->mail;
     $options = array();