Lightworks is a professional video editing tool that was open sourced in mid 2010. After a long delay, it may finally arrive in Linux this October. A Lightworks developer mentioned this in a forum thread:
We aim to have a Linux alpha build available on October 30th
Also, Lightworks in Ubuntu will have the same functionality and features as its Windows variant:
Lightworks on Ubuntu is virtually indistinguishable from the Windows version. There are some subtle differences in the fonts, but the core experience is deliberately the same. We want the editing experience to be identical, regardless of what the operating system is.
The above video shows Lightworks running in Ubuntu.