Brazilian journalist and documentarian Bruno Natal is working on a new film called Dub Echoes, that explores the history and influence of Jamaican dub music. Shot in Kingston, London, New York, Los Angeles, and Rio de Janeiro, the film talks to reggae legends like Mad Professor and Sly and Robbie, as well as producers like 2 Many DJ's and Thievery Corporation, whose work has been heavily influenced by dub.
The producers have just released a trailer, which looks very cool.
http://www.youtube.com/watch?v=wPz6lAa4y-I