The short story is that it’s an Adobe AIR-based app, built with Dojo itself, that gives you a zippy offline API documentation viewer and a graphical user interface for running Dojo builds.
This was my first interaction with the development side of AIR and my overall impression is quite good. The APIs are nicely done, and only having to target WebKit is quite a blessing.
My colleagues and I had a great time putting this together. Thanks to SitePen and Adobe for sponsoring this project!