The company bought the product - which was used on movies such as Shutter Island to the Oscar-winning Pulp Fiction - earlier this year. In April, EditShare announced plans to make Lightworks open source.
Lightworks includes the full range of features you would expect from a professional editing package, plus recent staples such as support for stereoscopic work, RED camera footage and a range of real-time effects. The software is GPU-accelerated.
As of two days ago, users can download the beta of the Windows edition of the Lightworks software for free. Linux and OS X versions will follow late next year.