Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.966
diff -u -r1.966 user.module
--- modules/user/user.module	26 Feb 2009 07:30:29 -0000	1.966
+++ modules/user/user.module	7 Mar 2009 20:48:34 -0000
@@ -237,15 +237,17 @@
  * Save changes to a user account or add a new user.
  *
  * @param $account
- *   The $user object for the user to modify or add. If $user->uid is
- *   omitted, a new user will be added.
+ *   (optional) The $user object to modify or add. If $account is an object
+ *   and $account->uid is non-empty, that user account will be modified.
+ *   Otherwise, a new user will be added.
  *
  * @param $edit
  *   An array of fields and values to save. For example array('name'
  *   => 'My name'). Keys that do not belong to columns in the user-related
  *   tables are added to the a serialized array in the 'data' column
  *   and will be loaded in the $user->data array by user_load().
- *   Setting a field to NULL deletes it from the data column.
+ *   Setting a field to NULL deletes it from the data column, if you are
+ *   modifying an existing user account.
  *
  * @param $category
  *   (optional) The category for storing profile information in.