Index: wp-admin/includes/media.php
===================================================================
--- wp-admin/includes/media.php	(revision 21203)
+++ wp-admin/includes/media.php	(working copy)
@@ -21,6 +21,9 @@
 		'library' => __('Media Library')
 	);
 
+	if ( isset( $_REQUEST['context'] ) && $_REQUEST['context'] == 'featured' )
+		unset( $_default_tabs['type_url'] );
+
 	return apply_filters('media_upload_tabs', $_default_tabs);
 }
 
Index: wp-admin/includes/post.php
===================================================================
--- wp-admin/includes/post.php	(revision 21203)
+++ wp-admin/includes/post.php	(working copy)
@@ -1147,7 +1147,9 @@
 	if ( empty( $post_id ) )
 		$post_id = $post_ID;
 
-	$upload_iframe_src = esc_url( get_upload_iframe_src('image', $post_id) );
+	$upload_iframe_src = get_upload_iframe_src( 'image', $post_id );
+	$upload_iframe_src = remove_query_arg( 'TB_iframe', $upload_iframe_src );
+	$upload_iframe_src = esc_url( add_query_arg( array( 'context' => 'featured', 'TB_iframe' => 1 ), $upload_iframe_src ) );
 	$set_thumbnail_link = '<p class="hide-if-no-js"><a title="' . esc_attr__( 'Set featured image' ) . '" href="%s" id="set-post-thumbnail" class="thickbox">%s</a></p>';
 	$content = sprintf( $set_thumbnail_link, $upload_iframe_src, esc_html__( 'Set featured image' ) );