Index: wp-admin/themes.php
===================================================================
--- wp-admin/themes.php	(revision 11948)
+++ wp-admin/themes.php	(working copy)
@@ -53,6 +53,7 @@
 		} else { ?>
 <div id="message2" class="updated fade"><p><?php printf(__('New theme activated. <a href="%s">Visit site</a>'), get_bloginfo('url') . '/'); ?></p></div><?php
 		}
+		do_action('activate_theme', get_current_theme());
 	elseif ( isset($_GET['deleted']) ) : ?>
 <div id="message3" class="updated fade"><p><?php _e('Theme deleted.') ?></p></div>
 <?php endif; ?>