According to Ausir over at The Vault, the DVD release of Mutant Chronicles includes an interview with Fallout narrator Ron Perlman during which he more-or-less confirms that a movie based on the post-apocalyptic video game franchise is being worked on.
...in the DVD commentary for the Mutant Chronicles movie, Ron Perlman stated that he was the narrator in a action heavy videogame that he thought was being made into a movie, and where the tagline was "War never changes". Is it an actual confirmation of the Fallout movie rumors, or maybe he's just mistaken? Fantasy movies are tough to pull off because of the huge cost associated with all the CGI that's required, but one would think that a movie shot in a post-nuclear wasteland probably wouldn't have quite so much overhead. If true, here's to hoping it gets done right.
We cannot be certain for now, but keep in mind that earlier this year Bethesda Softworks applied for the Fallout trademark for "Entertainment services in the nature of an on-going television program" and for "motion picture films about a post-nuclear apocalyptic world". So there might be some truth to the rumors, especially given that if a Fallout movie was being made, Ron Perlman would definitely be one of the first actors approached by the studio.