I recently finished reading an advance copy of Tim Keller's book, The Prodigal God: Recovering the Heart of the Christian Faith. As expected, it was excellent: challenging, convicting, and encouraging. Highly recommended.
In the book Keller talks about how listening to Edmund Clowney preach a sermon on this parable had a profound impact on him. "Listening to that sermon changed the way I understood Christianity. I almost felt I had discovered the secret heart of Christianity."
The Crossway blog is now making the written form of Clowney's original sermon available online for free.