Index: wp-includes/js/tinymce/plugins/wpeditimage/css/editimage.css
===================================================================
--- wp-includes/js/tinymce/plugins/wpeditimage/css/editimage.css	(revision 23035)
+++ wp-includes/js/tinymce/plugins/wpeditimage/css/editimage.css	(working copy)
@@ -97,6 +97,14 @@
 	padding: 0;
 }
 
+img#img_demo.alignleft {
+	float: left;
+}
+
+img#img_demo.alignright {
+	float: right;
+}
+
 #saveeditimg {
 	padding: 10px 0 0 5px;
 	border-top: 1px solid #ccc;