PeteS [inclind]

function menu_multiple_node_menu_install() {
  return;
}

There is no need to define an install function that doesn't do anything.

Some minor nitpicks:
- I'd remove the package = User interface from the .info since you are not part of a larger module package like Views or CCK.
- Make sure to also remove the last four lines from the .info file as that is going to be added by the drupal.org packaging script automatically, so you should not have those lines in the CVS versions.
- Your access controls on the JS callback should really check user_access('administer menu') and not 'access content' since you are working with menus. This also matches the permission used for actions in menu.module.

Otherwise I think everything looks really really good. Very nice work with this.
-