Don't give away the film's ending by actually reading the book

So the chattering Hollywood classes are all agog at Will Smith accidentally giving away the ending to the upcoming film I Am Legend. Of course, anyone who has actually read Richard Matheson's 1954 novel of the same title probably has a decent idea what the mysterious ending is (unless Hollywood has totally butchered the storyline, which would be another reason to be all agog). Why do I suspect the people worrying about keeping the film's ending secret are all people who haven't read a single book in the last ten years?

UPDATE: Of course, one also hopes the director wasn't stupid enough to give the movie a happy Hollywood ending. But I'm not betting against it.