The unreliable narrator isn't a new tool. In fact, it's very old, but I think it's one that could be used more often (are you listening, film industry?!) to add new twists, turns, etc. Finding out at the end of the novel that everything you thought was going on was really skewed makes for a really unique experience. Nothing beats that "Wait, wait...HUH?!" reaction at the end of a book or movie, especially in a time when a lot of what the entertainment industry produces is so utterly predictable.
So next time you're thinking about writing, or filming, or even if you're the one doing the reading or watching, give a thought to this neat little tool and how it can make things so much more interesting. :)