Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.892.2.14
diff -u -r1.892.2.14 user.module
--- modules/user/user.module	1 Jul 2009 20:51:56 -0000	1.892.2.14
+++ modules/user/user.module	10 Jul 2009 22:01:55 -0000
@@ -193,14 +193,17 @@
  * 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 you want to modify
+ *   an existing user account, you will need to ensure that (a) $account 
+ *   is an object, and (b) you have set $account->uid to the numeric 
+ *   user ID of the user account you wish to modify.
  * @param $array
  *   (optional) An array of fields and values to save. For example,
- *   array('name' => 'My name'); Setting a field to NULL deletes it from
- *   the data column.
- *
+ *   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, 
+ *   if you are modifying an existing user account.
  * @param $category
  *   (optional) The category for storing profile information in.
  *