François Beaune, software architect and member of the /*jupiter jazz*/ group, has been working on a renderer for some time, the name is appleseed.

François is not new to this kind of challenges, he wrote and managed one of the first OpenSource Global Illumination renderers: toxic.

appleseed is as well open source, released under the very permissive MIT license, it is targeted to renderer enthusiast and software developers. With at the core an ununbiased spectral-based forward path tracer, it features a very clean and structured codebase, ideal for further collaborative development, and it is available on Windows and Darwin (OSX) platforms.

Wrapped into a Qt framework, appleseed studio allows the user to interact and navigate the scene while progressively rendering, here you can see a video of the workflow:

You can access the appleseed source on GitHub.

For more informations check the project website: appleseedhq.net

And here another image: