Film distribution gets more and more eccentric. Warner Brothers has announced that it is joining with Facebook to allow US film fans to rent movies through the irritating social-network site. For $3, the user will be granted a 48-hour window to watch the movie of his or her choice. The first film available is, not surprisingly, The Dark Knight.

"Facebook has become a daily destination for hundreds of millions of people," said the studio. "Making our films available through Facebook is a natural extension of our digital distribution efforts." But surely everybody on Facebook already has a copy of The Dark Knight?