Yeah. After H2g2, it's Simon Mayo from Five Live Radio that will offer a small part in the hitchhiker's movie Monday on his show (from 1 to 4pm BST): "Five Live is offering one lucky person the chance to act alongside Hollywood stars in the new Hitchhikers Guide to the Galaxy movie. The winner of the competition which will be launched on the Simon Mayo programme on Monday 5 July will spend a day on location and could be in the final cut of the film!"
An extract of the terms and conditions are here : "The winner must be over 18 years. The winner must be able to attend a costume fitting session on either July 8 or 9 and attend full days shooting in London July 19. The winner will receive £100 to cover travel expenses. The extra's role may not appear in the final version of the film. The decision of the film's Director is final" It's not said if you've got to live in UK to participate, but well i guess that was the case too with the h2g2 competition.