6 theme calls to theme_status_messages()

ajax_prepare_response in drupal/core/includes/ajax.inc
Converts the return value of a page callback into an Ajax commands array.
file_ajax_upload in drupal/core/modules/file/file.module
Ajax callback: Processes file uploads and deletions.
hook_ajax_render_alter in drupal/core/modules/system/system.api.php
Alter the commands that are sent to the user through the Ajax framework.
template_preprocess_maintenance_page in drupal/core/includes/theme.inc
The variables array generated here is a mirror of template_preprocess_page(). This preprocessor will run its course when theme_maintenance_page() is invoked.
template_process_page in drupal/core/includes/theme.inc
Process variables for page.tpl.php
views_ajax_form_wrapper in drupal/core/modules/views/includes/ajax.inc
Wrapper around drupal_build_form to handle some AJAX stuff automatically. This makes some assumptions about the client.