If I recall correctly, the connection between Oubliette and this story is that Oubliette comes from the same root as the English word "Oblivion." The idea of an Oubliette is that you throw someone you don't like down there, leave orders for her to be fed and watered occasionally, and then... forget about her. Forever.
I think the idea is that the main character is similarly imprisoned. He can't forget, but since the memory is so thoroughly imprisoned, he may as well.
Anyway, I loved this one. Classic, clever, slightly-tongue-in-cheek sci-fi at its best. Not terribly remarkable, but fun and clever. Four Zeppelins.