BBC Four is currently re-runing a fantastic six-part documentary series entitled 'The Genius Of Photography'. I have seen it previously and cannot recommend it highly enough. The series starts with the first days of photography in its' earliest forms, travelling through daguerrotypes to digital and looking at the work of some incredible photographers along the way. I found it to be not only a very impressive and well put together series, but also deeply inspiring and thought-provoking.

Full details can be found here - http://www.bbc.co.uk/programmes/b00859t3