Update D6 layout plugins for D7, create module .inc w/

example.module

<?php

/**
 * Implementation of hook_ctools_plugin_api().
 *
 * Inform CTools about version information for various plugins implemented by
 * Panels.
 *
 * @param string $owner
 *   The system name of the module owning the API about which information is
 *   being requested.
 * @param string $api
 *   The name of the API about which information is being requested.
 */
function themename_plugins_ctools_plugin_api($owner, $api) {
  if ($owner == 'panels' && $api == 'layout') {
    return array('version' => 2.0);
  }
}

/**
 * Implements of hook_ctools_plugin_directory().
 */
function themename_plugins_ctools_plugin_directory($module, $plugin) {
  return 'plugins/' . $plugin;
}

gistfile1.txt

name = D7 Plugins
description = Provides CTools plugins for use by ThemeName
core = 7.x

The plugin directories with calls to hook_panels_layouts should be fine.