Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 14499)
+++ wp-includes/post.php	(working copy)
@@ -681,23 +681,30 @@
 }
 
 /**
- * Checks if a post type is registered. Can also check if the current or specified post is of a post type.
+ * Check if a post type is registered.
  *
  * @since 3.0.0
+ * @uses get_post_type_object()
+ *
+ * @param string $types Type to check.
+ * @return bool
+ */
+function is_post_type( $type ) {
+	return (bool) get_post_type_object($type);
+}
+
+/**
+ * Check if the current or specified post is of a given post type.
+ *
+ * @since 3.0.0
  * @uses get_post_type()
  *
- * @param string|array $types Type or types to check. Defaults to all post types.
+ * @param string|array $types Type or types to check.
  * @param int $id Post ID. Defaults to current ID.
  * @return bool
  */
-function is_post_type( $types = false, $id = false ) {
-	if ( $id ) {
-		$types = ( $types === false ) ? get_post_types() : (array) $types;
-
-		return in_array( get_post_type( $id ), $types );
-	}
-
-	return (bool) get_post_type_object($types);
+function is_post_of_type( $types, $id = false ) {
+	return in_array( get_post_type( $id ), (array) $types );
 }
 
 /**