Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 21825)
+++ wp-includes/query.php	(working copy)
@@ -2362,7 +2362,12 @@
 						break;
 					case $q['meta_key']:
 					case 'meta_value':
-						$orderby = "$wpdb->postmeta.meta_value";
+						if ( isset( $q['meta_type'] ) ) {
+							$meta_type = get_meta_type( $q['meta_type'] );
+							$orderby = "CAST($wpdb->postmeta.meta_value AS {$meta_type})";
+						} else {
+							$orderby = "$wpdb->postmeta.meta_value";
+						}	
 						break;
 					case 'meta_value_num':
 						$orderby = "$wpdb->postmeta.meta_value+0";
Index: wp-includes/meta.php
===================================================================
--- wp-includes/meta.php	(revision 21825)
+++ wp-includes/meta.php	(working copy)
@@ -604,6 +604,30 @@
 }
 
 /**
+ * Given a meta type, return the appropriate alias if applicable
+ *
+ * @since 3.5.0
+ *
+ * @see WP_Meta_Query
+ *
+ * @param string $type MySQL type to cast meta_value
+ * @return string MySQL type
+ */
+function get_meta_type( $type = '' ) {
+	if ( empty( $type ) )
+		return 'CHAR';
+	
+	$meta_type = strtoupper( $type );
+
+	if ( ! in_array( $meta_type, array( 'BINARY', 'CHAR', 'DATE', 'DATETIME', 'DECIMAL', 'SIGNED', 'TIME', 'UNSIGNED', 'NUMERIC' ) ) )	
+		return 'CHAR';
+			
+	if ( 'NUMERIC' == $meta_type )
+		$meta_type = 'SIGNED';
+
+	return $meta_type;
+}
+/**
  * Container class for a multiple metadata query
  *
  * @since 3.2.0
@@ -713,13 +737,8 @@
 
 		foreach ( $this->queries as $k => $q ) {
 			$meta_key = isset( $q['key'] ) ? trim( $q['key'] ) : '';
-			$meta_type = isset( $q['type'] ) ? strtoupper( $q['type'] ) : 'CHAR';
+			$meta_type = get_meta_type( isset( $q['type'] ) ? $q['type'] : '' );
 
-			if ( 'NUMERIC' == $meta_type )
-				$meta_type = 'SIGNED';
-			elseif ( ! in_array( $meta_type, array( 'BINARY', 'CHAR', 'DATE', 'DATETIME', 'DECIMAL', 'SIGNED', 'TIME', 'UNSIGNED' ) ) )
-				$meta_type = 'CHAR';
-
 			$meta_value = isset( $q['value'] ) ? $q['value'] : null;
 
 			if ( isset( $q['compare'] ) )