Index: wp-activate.php
===================================================================
--- wp-activate.php	(revision 31574)
+++ wp-activate.php	(working copy)
@@ -14,7 +14,7 @@
 require( dirname( __FILE__ ) . '/wp-blog-header.php' );
 
 if ( !is_multisite() ) {
-	wp_redirect( site_url( '/wp-login.php?action=register' ) );
+	wp_redirect( wp_registration_url() );
 	die();
 }
 
@@ -107,6 +107,9 @@
 		} else {
 			$url = isset( $result['blog_id'] ) ? get_blogaddress_by_id( (int) $result['blog_id'] ) : '';
 			$user = get_userdata( (int) $result['user_id'] );
+			switch_to_blog( (int) $result['blog_id'] );
+			$login_url = wp_login_url();
+			restore_current_blog();
 			?>
 			<h2><?php _e('Your account is now active!'); ?></h2>
 
@@ -116,7 +119,7 @@
 			</div>
 
 			<?php if ( $url && $url != network_home_url( '', 'http' ) ) : ?>
-				<p class="view"><?php printf( __('Your account is now activated. <a href="%1$s">View your site</a> or <a href="%2$s">Log in</a>'), $url, $url . 'wp-login.php' ); ?></p>
+				<p class="view"><?php printf( __('Your account is now activated. <a href="%1$s">View your site</a> or <a href="%2$s">Log in</a>'), $url, esc_url( $login_url ) ); ?></p>
 			<?php else: ?>
 				<p class="view"><?php printf( __('Your account is now activated. <a href="%1$s">Log in</a> or go back to the <a href="%2$s">homepage</a>.' ), network_site_url('wp-login.php', 'login'), network_home_url() ); ?></p>
 			<?php endif;
Index: wp-admin/install.php
===================================================================
--- wp-admin/install.php	(revision 31574)
+++ wp-admin/install.php	(working copy)
@@ -156,7 +156,7 @@
 // Let's check to make sure WP isn't already installed.
 if ( is_blog_installed() ) {
 	display_header();
-	die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p><p class="step"><a href="../wp-login.php" class="button button-large">' . __( 'Log In' ) . '</a></p></body></html>' );
+	die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p><p class="step"><a href="' . esc_url( wp_login_url() ) . '" class="button button-large">' . __( 'Log In' ) . '</a></p></body></html>' );
 }
 
 global $wp_version, $required_php_version, $required_mysql_version;
@@ -291,7 +291,7 @@
 	</tr>
 </table>
 
-<p class="step"><a href="../wp-login.php" class="button button-large"><?php _e( 'Log In' ); ?></a></p>
+<p class="step"><a href="<?php echo esc_url( wp_login_url() ); ?>" class="button button-large"><?php _e( 'Log In' ); ?></a></p>
 
 <?php
 		}
Index: wp-admin/network.php
===================================================================
--- wp-admin/network.php	(revision 31574)
+++ wp-admin/network.php	(working copy)
@@ -526,7 +526,7 @@
 	<?php endif; // end IIS/Apache code branches.
 
 	if ( !is_multisite() ) { ?>
-		<p><?php printf( __( 'Once you complete these steps, your network is enabled and configured. You will have to log in again.') ); ?> <a href="<?php echo esc_url( site_url( 'wp-login.php' ) ); ?>"><?php _e( 'Log In' ); ?></a></p>
+		<p><?php printf( __( 'Once you complete these steps, your network is enabled and configured. You will have to log in again.') ); ?> <a href="<?php echo esc_url( wp_login_url() ); ?>"><?php _e( 'Log In' ); ?></a></p>
 <?php
 	}
 }
Index: wp-includes/canonical.php
===================================================================
--- wp-includes/canonical.php	(revision 31574)
+++ wp-includes/canonical.php	(working copy)
@@ -319,7 +319,7 @@
 				/** This filter is documented in wp-login.php */
 				$redirect_url = apply_filters( 'wp_signup_location', network_site_url( 'wp-signup.php' ) );
 			} else {
-				$redirect_url = site_url( 'wp-login.php?action=register' );
+				$redirect_url = wp_registration_url();
 			}
 
 			wp_redirect( $redirect_url, 301 );
@@ -576,7 +576,7 @@
 		site_url( 'login', 'relative' ),
 	);
 	if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $logins ) ) {
-		wp_redirect( site_url( 'wp-login.php', 'login' ) );
+		wp_redirect( wp_login_url() );
 		exit;
 	}
 }
Index: wp-signup.php
===================================================================
--- wp-signup.php	(revision 31574)
+++ wp-signup.php	(working copy)
@@ -28,7 +28,7 @@
 add_action( 'wp_head', 'do_signup_header' );
 
 if ( !is_multisite() ) {
-	wp_redirect( site_url('wp-login.php?action=register') );
+	wp_redirect( wp_registration_url() );
 	die();
 }
 
@@ -353,8 +353,13 @@
 	 */
 	$meta = apply_filters( 'add_signup_meta', $meta_defaults );
 
-	wpmu_create_blog( $domain, $path, $blog_title, $current_user->ID, $meta, $wpdb->siteid );
-	confirm_another_blog_signup($domain, $path, $blog_title, $current_user->user_login, $current_user->user_email, $meta);
+	$blog_id = wpmu_create_blog( $domain, $path, $blog_title, $current_user->ID, $meta, $wpdb->siteid );
+
+	if ( is_wp_error( $blog_id ) ) {
+		return false;
+	}
+
+	confirm_another_blog_signup( $domain, $path, $blog_title, $blog_id, $current_user->user_login );
 	return true;
 }
 
@@ -365,15 +370,18 @@
  *
  * @param string $domain The domain URL
  * @param string $path The site root path
+ * @param string $blog_title The blog title
+ * @param string $blog_id The blog ID
  * @param string $user_name The username
- * @param string $user_email The user's email address
- * @param array $meta Any additional meta from the 'add_signup_meta' filter in validate_blog_signup()
  */
-function confirm_another_blog_signup( $domain, $path, $blog_title, $user_name, $user_email = '', $meta = array() ) {
+function confirm_another_blog_signup( $domain, $path, $blog_title, $blog_id, $user_name ) {
+	switch_to_blog( $blog_id );
+	$login_url = wp_login_url();
+	restore_current_blog();
 	?>
-	<h2><?php printf( __( 'The site %s is yours.' ), "<a href='http://{$domain}{$path}'>{$blog_title}</a>" ) ?></h2>
+	<h2><?php printf( __( 'The site %s is yours.' ), "<a href='http://{$domain}{$path}'>{$blog_title}</a>" ); ?></h2>
 	<p>
-		<?php printf( __( '<a href="http://%1$s">http://%2$s</a> is your new site. <a href="%3$s">Log in</a> as &#8220;%4$s&#8221; using your existing password.' ), $domain.$path, $domain.$path, "http://" . $domain.$path . "wp-login.php", $user_name ) ?>
+		<?php printf( __( '<a href="http://%1$s">http://%2$s</a> is your new site. <a href="%3$s">Log in</a> as &#8220;%4$s&#8221; using your existing password.' ), $domain.$path, $domain.$path, $login_url, $user_name ); ?>
 	</p>
 	<?php
 	/**
@@ -669,7 +677,7 @@
 if ( $active_signup == 'none' ) {
 	_e( 'Registration has been disabled.' );
 } elseif ( $active_signup == 'blog' && !is_user_logged_in() ) {
-	$login_url = site_url( 'wp-login.php?redirect_to=' . urlencode( network_site_url( 'wp-signup.php' ) ) );
+	$login_url = wp_login_url( network_site_url( 'wp-signup.php' ) );
 	echo sprintf( __( 'You must first <a href="%s">log in</a>, and then you can create a new site.' ), $login_url );
 } else {
 	$stage = isset( $_POST['stage'] ) ?  $_POST['stage'] : 'default';