This is a great program, I did it concurrently with YC s09. They're not really an incubator - John, who runs the program, wants to give smart grads the freedom to get a taste of what its like to be an entrepreneur. Several partners act as mentors but its really about giving you the space and money for a summer to see if you can make something happen.
What do they get? They get to know really smart entrepreneurs at the beginning of their career. I highly recommend you apply.