An artist named Spencer Tunick has a project going. After making all the proper arrangements and issuing calls for volunteers, he photographs large groups of people in the nude. Last weekend in Melbourne, four thousand of them showed up. Here’s one account of it. Here’s another. And here’s a gallery of the photos, beautiful or unnerving depending on your take, of four thousand cheerfully unclothed and goosefleshed Australians looking like some strange migratory species.