Index: wp-signup.php
===================================================================
--- wp-signup.php	(revision 23226)
+++ wp-signup.php	(working copy)
@@ -165,10 +165,14 @@
 	if ( $errors->get_error_code() ) {
 		echo '<p>' . __( 'There was a problem, please correct the form below and try again.' ) . '</p>';
 	}
-	?>
-	<p><?php printf( __( 'Welcome back, %s. By filling out the form below, you can <strong>add another site to your account</strong>. There is no limit to the number of sites you can have, so create to your heart&#8217;s content, but write responsibly!' ), $current_user->display_name ) ?></p>
 
-	<?php
+	if ( $add_another_site_message = apply_filters( 'add_another_site_message', __( 'Welcome back, %s. By filling out the form below, you can <strong>add another site to your account</strong>. There is no limit to the number of sites you can have, so create to your heart&#8217;s content, but write responsibly!' ) ) ) {
+		?>
+		<p><?php printf( $add_another_site_message, $current_user->display_name ) ?></p>
+	
+		<?php
+	}
+
 	$blogs = get_blogs_of_user($current_user->ID);
 	if ( !empty($blogs) ) { ?>