It's called "Shaking Hands With Death" and will be on BBC One on 1 February, 2010.
BBC News - Sir Terry Pratchett to give Richard Dimbleby lecture
Author Sir Terry Pratchett will deliver the 34th annual Richard Dimbleby Lecture, held in honour of the veteran broadcaster, the BBC has announced.
Writer of the bestselling Discworld series, Sir Terry revealed he was suffering from a rare form of early-onset Alzheimer's disease in 2007.
His lecture will explore how modern society needs to redefine how it deals with death.
BBC News - Sir Terry Pratchett to give Richard Dimbleby lecture