I implemented the script as a command and came to post here to complain that it wouldn't undo, but you have beaten me to it :)

Copying all of the geometry by a clone is a very heavyweight operation for a simple re-name. Is it possible to add the name field to your undo system?

edit: how does the current system work when I click on the top left name field and type in a new name? I can undo that operation, is this also a completely clone of all geometry that is being renamed?