Jacquelene Cohen, director of publicity & promotions for Fantagraphics Books, emailed me the following:
Shia LaBeouf's new short film, HowardCantour.com, is a complete rip off of Daniel Clowes's comic "Justin M. Damiano." Every-word from the 4 page comic created by Clowes in 2006 is used in the script for LaBeouf's directional debut. Clowes never authorized the use of his comic for HowardCantour.com. He had no knowledge that he had been plagiarized until today when the film was posted on Vimeo.
Comic Book Alliance has more:
The film, which was posted online earlier today but has since been removed, shares several similarities with Clowes' short story, with lines that are lifted directly from the comic. Yet in an interview with the website Short of the Week, LaBeouf, who has been accused of plagiarism in the past, claims to have come up with the concept for the film organically, having been inspired by negative reviews he received for his lackluster comics work, as well as the films he has reportedly appeared in.