Index: pluggable.php
===================================================================
--- pluggable.php	(revision 12021)
+++ pluggable.php	(working copy)
@@ -1154,6 +1154,8 @@
 	$message .= sprintf(__('Username: %s'), $user_login) . "\r\n\r\n";
 	$message .= sprintf(__('E-mail: %s'), $user_email) . "\r\n";
 
+    $message = apply_filters( 'admin_new_user_notification', $message );
+
 	@wp_mail(get_option('admin_email'), sprintf(__('[%s] New User Registration'), get_option('blogname')), $message);
 
 	if ( empty($plaintext_pass) )
@@ -1163,6 +1165,8 @@
 	$message .= sprintf(__('Password: %s'), $plaintext_pass) . "\r\n";
 	$message .= wp_login_url() . "\r\n";
 
+    $message = apply_filters( 'new_user_notification', $message );
+
 	wp_mail($user_email, sprintf(__('[%s] Your username and password'), get_option('blogname')), $message);
 
 }