Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 15211)
+++ wp-includes/formatting.php	(working copy)
@@ -2402,6 +2402,7 @@
 		case 'mailserver_port':
 		case 'comment_max_links':
 		case 'page_on_front':
+		case 'page_for_posts':
 		case 'rss_excerpt_length':
 		case 'default_category':
 		case 'default_email_category':
Index: wp-admin/includes/schema.php
===================================================================
--- wp-admin/includes/schema.php	(revision 15211)
+++ wp-admin/includes/schema.php	(working copy)
@@ -314,6 +314,10 @@
 	'embed_autourls' => 1,
 	'embed_size_w' => '',
 	'embed_size_h' => 600,
+
+	// 3.0
+	'page_for_posts' => 0,
+	'page_on_front' => 0,
 	);
 
 	// 3.0 multisite
Index: wp-admin/options-reading.php
===================================================================
--- wp-admin/options-reading.php	(revision 15211)
+++ wp-admin/options-reading.php	(working copy)
@@ -38,7 +38,10 @@
 <?php if ( ! get_pages() ) : ?>
 <input name="show_on_front" type="hidden" value="posts" />
 <table class="form-table">
-<?php else : ?>
+<?php else :
+	if ( 'page' == get_option( 'show_on_front' ) && ! get_option( 'page_on_front' ) && ! get_option( 'page_for_posts' ) )
+		update_option( 'show_on_front', 'posts' );
+?>
 <table class="form-table">
 <tr valign="top">
 <th scope="row"><?php _e( 'Front page displays' ); ?></th>
@@ -54,8 +57,8 @@
 	</label>
 	</p>
 <ul>
-	<li><label for="page_on_front"><?php printf( __( 'Front page: %s' ), wp_dropdown_pages( array( 'name' => 'page_on_front', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'selected' => get_option( 'page_on_front' ) ) ) ); ?></label></li>
-	<li><label for="page_for_posts"><?php printf( __( 'Posts page: %s' ), wp_dropdown_pages( array( 'name' => 'page_for_posts', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'selected' => get_option( 'page_for_posts' ) ) ) ); ?></label></li>
+	<li><label for="page_on_front"><?php printf( __( 'Front page: %s' ), wp_dropdown_pages( array( 'name' => 'page_on_front', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'option_none_value' => '0', 'selected' => get_option( 'page_on_front' ) ) ) ); ?></label></li>
+	<li><label for="page_for_posts"><?php printf( __( 'Posts page: %s' ), wp_dropdown_pages( array( 'name' => 'page_for_posts', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'option_none_value' => '0', 'selected' => get_option( 'page_for_posts' ) ) ) ); ?></label></li>
 </ul>
 <?php if ( 'page' == get_option( 'show_on_front' ) && get_option( 'page_for_posts' ) == get_option( 'page_on_front' ) ) : ?>
 <div id="front-page-warning" class="error inline"><p><?php _e( '<strong>Warning:</strong> these pages should not be the same!' ); ?></p></div>