Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 24072)
+++ wp-includes/post.php	(working copy)
@@ -2331,6 +2331,20 @@
 	$post['post_status'] = 'trash';
 	wp_insert_post($post);
 
+	if ( 'page' == $post['post_type'] ) {
+		// if the page is defined in option page_on_front or post_for_posts,
+		// adjust the corresponding options
+		if ( get_option('page_on_front') == $post_id ) {
+			update_option('show_on_front', 'posts');
+			delete_option('page_on_front');
+		}
+		if ( get_option('page_for_posts') == $post_id ) {
+			delete_option('page_for_posts');
+		}
+	} else {
+		unstick_post( $post_id );
+	}
+
 	wp_trash_post_comments($post_id);
 
 	do_action('trashed_post', $post_id);