Behold: the book trailer for the new Thomas Pynchon novel Inherent Vice. 
The scuttlebutt on the Internets is that the person doing the voiceover may or may not be the reclusive author himself.
The only thing to go by, I guess, would be to compare the voiceover bit he did on The Simpsons a few years ago.
I don’t know. Sounds like it could be him to me. I like to think it’s him. So it’s him.