Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.1002
diff -u -r1.1002 user.module
--- modules/user/user.module	22 Jun 2009 09:10:07 -0000	1.1002
+++ modules/user/user.module	26 Jun 2009 15:03:04 -0000
@@ -352,16 +352,16 @@
  * 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 (or $user->is_new == TRUE), a new user will be added.
- *
+ *   (optional) The $user object to modify or add. If $account is an object,
+ *   $account->uid is non-empty, and $account->is_new is false or 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.
  *