Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 12596)
+++ wp-includes/post.php	(working copy)
@@ -15,8 +15,8 @@
  * Creates the initial post types when 'init' action is fired.
  */
 function create_initial_post_types() {
-	register_post_type( 'post', array('exclude_from_search' => false) );
-	register_post_type( 'page', array('exclude_from_search' => false) );
+	register_post_type( 'post', array('exclude_from_search' => false, 'revisions' => true) );
+	register_post_type( 'page', array('exclude_from_search' => false, 'revisions' => true) );
 	register_post_type( 'attachment', array('exclude_from_search' => false) );
 	register_post_type( 'revision', array('exclude_from_search' => true) );
 }
@@ -3728,7 +3728,7 @@
 	if ( !$post = get_post( $post_id, ARRAY_A ) )
 		return;
 
-	if ( !in_array( $post['post_type'], array( 'post', 'page' ) ) )
+	if ( !in_array( $post['post_type'], get_post_types( array('revisions' => true) ) ) )
 		return;
 
 	$return = _wp_put_post_revision( $post );
@@ -3740,7 +3740,7 @@
 	// all revisions and (possibly) one autosave
 	$revisions = wp_get_post_revisions( $post_id, array( 'order' => 'ASC' ) );
 
-	// WP_POST_REVISIONS = (int) (# of autasaves to save)
+	// WP_POST_REVISIONS = (int) (# of autosaves to save)
 	$delete = count($revisions) - WP_POST_REVISIONS;
 
 	if ( $delete < 1 )