ONLY show update notification for admin users (as opposed to just the user ‘admin’):

// REMOVE THE WORDPRESS UPDATE NOTIFICATION FOR ALL USERS EXCEPT SYSADMIN
       global $user_login;
       get_currentuserinfo();
       if (!current_user_can('update_plugins')) { // checks to see if current user can update plugins 
        add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
        add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
       }