Lightworks, a professional non-linear video editor, is now available as open source. Their website hasn't been fully updated yet, so I can't say under exactly *which* license is has been released. Lightworks is Windows-only at the moment.
From the website:
The Lightworks Open Source Project starts here...
Back in April 2010,we announced our plans to take Lightworks open source and the first stage in doing that was to make the application freely available. So we are very pleased to reach this first stage and offer a free download of the most intuitive and advanced editor available. Lightworks is an Academy and Emmy award winning professional-grade editor with over 20 years of history in the film and broadcast industry. Having cut hundreds of films such as Pulp Fiction, The Departed, Centurion and Shutter Island, it includes a full feature set of editorial tools, from advanced trimming and media management, through to stereoscopic support and realtime effects including multiple secondary colour correctors. Lightworks has an advanced effects pipeline, utilizing the power of your GPU. And with support for up to 2K workflows with realtime effects, it is the most advanced editing application available.
There have been many reports of this over the past few months, but I decided to hold off publication until it really happened.