--- conditional_fields.old      2011-06-29 09:45:42.414710810 -0700
+++ conditional_fields.module   2011-06-29 09:47:30.927343917 -0700
@@ -824,7 +824,19 @@ function conditional_fields_check_empty(
   elseif (isset($field[0]['nid'])) {
     $value = $field[0]['nid'];
   }
-
+  // User reference
+  elseif (isset($field[0]['uid'])) {
+    $value = $field[0]['uid'];
+  }
+  // Role reference
+  elseif (isset($field[0]['rid'])) {
+    $value = $field[0]['rid'];
+  }
+  // Email field
+  elseif (isset($field[0]['email'])) {
+    $value = $field[0]['email'];
+  }
+
   if (!count($value) || (is_string($value) && drupal_strlen(trim($value)) == 0)) {
     return TRUE;
   }