Index: wp-admin/admin-header.php
===================================================================
--- wp-admin/admin-header.php	(revision 18222)
+++ wp-admin/admin-header.php	(working copy)
@@ -151,6 +151,8 @@
 
 // Generate user profile and info links.
 $howdy = sprintf( __('Howdy, %1$s'), $user_identity );
+$howdy = apply_filters( 'admin_user_greeting', $howdy, $user_identity );
+
 $links = array();
 
 $links[5] = '<a href="profile.php" title="' . esc_attr__('Edit your profile') . '">' . __('Your Profile') . '</a>';