Index: bp-themes/bp-default/registration/register.php
===================================================================
--- bp-themes/bp-default/registration/register.php	(revision 3113)
+++ bp-themes/bp-default/registration/register.php	(working copy)
@@ -180,7 +180,7 @@
 							<label for="signup_blog_url"><?php _e( 'Blog URL', 'buddypress' ) ?> <?php _e( '(required)', 'buddypress' ) ?></label>
 							<?php do_action( 'bp_signup_blog_url_errors' ) ?>
 
-							<?php if ( 'yes' == VHOST ) : ?>
+							<?php if ( is_subdomain_install() ) : ?>
 								http:// <input type="text" name="signup_blog_url" id="signup_blog_url" value="<?php bp_signup_blog_url_value() ?>" /> .<?php echo str_replace( 'http://', '', site_url() ) ?>
 							<?php else : ?>
 								<?php echo site_url() ?>/ <input type="text" name="signup_blog_url" id="signup_blog_url" value="<?php bp_signup_blog_url_value() ?>" />
@@ -307,4 +307,4 @@
 		});
 	</script>
 
-<?php get_footer() ?>
\ No newline at end of file
+<?php get_footer() ?>
Index: bp-core/bp-core-wpabstraction.php
===================================================================
--- bp-core/bp-core-wpabstraction.php	(revision 3113)
+++ bp-core/bp-core-wpabstraction.php	(working copy)
@@ -89,3 +89,12 @@
 		return true;
 	}
 }
+
+if ( !function_exists( 'is_subdomain_install' ) ) {
+	function is_subdomain_install() {
+		if ( ( defined( 'VHOST' ) && 'yes' == VHOST ) || ( defined( 'SUBDOMAIN_INSTALL' ) && SUBDOMAIN_INSTALL ) )
+			return true;
+
+		return false;
+	}
+}
Index: bp-core/bp-core-catchuri.php
===================================================================
--- bp-core/bp-core-catchuri.php	(revision 3113)
+++ bp-core/bp-core-catchuri.php	(working copy)
@@ -135,7 +135,7 @@
 	if ( !isset($is_root_component) )
 		$is_root_component = in_array( $bp_uri[0], $bp->root_components );
 
-	if ( 'no' == VHOST && !$is_root_component ) {
+	if ( !is_subdomain_install() && !$is_root_component ) {
 		$component_index++;
 		$action_index++;
 	}
@@ -154,7 +154,7 @@
 	unset($action_variables[$action_index]);
 
 	/* Remove the username from action variables if this is not a VHOST install */
-	if ( 'no' == VHOST && !$is_root_component )
+	if ( !is_subdomain_install() && !$is_root_component )
 		array_shift($action_variables);
 
 	/* Reset the keys by merging with an empty array */
@@ -283,4 +283,4 @@
 		bp_core_load_template( apply_filters( 'bp_core_template_display_profile', 'members/single/home' ) );
 }
 
-?>
\ No newline at end of file
+?>
Index: bp-blogs/bp-blogs-templatetags.php
===================================================================
--- bp-blogs/bp-blogs-templatetags.php	(revision 3113)
+++ bp-blogs/bp-blogs-templatetags.php	(working copy)
@@ -361,7 +361,7 @@
 	global $current_site;
 
 	// Blog name
-	if( 'no' == constant( "VHOST" ) )
+	if( !is_subdomain_install() )
 		echo '<label for="blogname">' . __('Blog Name:', 'buddypress') . '</label>';
 	else
 		echo '<label for="blogname">' . __('Blog Domain:', 'buddypress') . '</label>';
@@ -370,14 +370,14 @@
 		<p class="error"><?php echo $errmsg ?></p>
 	<?php }
 
-	if( 'no' == constant( "VHOST" ) ) {
+	if( !is_subdomain_install() ) {
 		echo '<span class="prefix_address">' . $current_site->domain . $current_site->path . '</span> <input name="blogname" type="text" id="blogname" value="'.$blogname.'" maxlength="50" /><br />';
 	} else {
 		echo '<input name="blogname" type="text" id="blogname" value="'.$blogname.'" maxlength="50" /> <span class="suffix_address">.' . $current_site->domain . $current_site->path . '</span><br />';
 	}
 	if ( !is_user_logged_in() ) {
 		print '(<strong>' . __( 'Your address will be ' , 'buddypress');
-		if( 'no' == constant( "VHOST" ) ) {
+		if( !is_subdomain_install() ) {
 			print $current_site->domain . $current_site->path . __( 'blogname' , 'buddypress');
 		} else {
 			print __( 'domain.' , 'buddypress') . $current_site->domain . $current_site->path;
@@ -499,4 +499,4 @@
 <?php
 }
 
-?>
\ No newline at end of file
+?>