From the announcement:
I've received an email from Scott Pyle (the author of the SuperSystem 3 rules) today. He will be generously donating a free copy of the SuperSystem 3rd ed. PDF to backers from the Henchman Boss level and up! So anyone contributing $44 or more to the project will receive them when the rewards ship. This was a fantastic way to increase the value of our project without increasing the cost to the backers.
This is a great opportunity and one that will allow you to peruse a great little game system if you haven't already. You can spend hours just reading through the character build system. This PDF makes a fine addition to our project!
We believe that any time a project in our little niche is successful, we are all successful. So pass the word around!
Onwards and upwards!