While it was never open source, it looks like they’ve taken it behind a paid wall. They do have a trial version limited to 5,000 posts, but it’s encoded and you have to have the Zend Optimizer or IonCube on your server to run it.
Too bad. While I appreciate everyone’s right to make a living, this app was so useful for a lot of the non-profit organizations I work with. It’s now $59 a year. Still worth it, in my opinion.