There's a number of open-source non-linear video editor programs that have been going for a few years, including Cinelerra, OpenShot, and PiTiVi, among others. None of these projects have been particularly promising and yet comparable to the proprietary competition in the video editing world. Lightworks is an option since it's a professional software product that was then open-sourced, but it's Linux client isn't expected until late 2011. There is though another new option coming in the Linux video world and that's Novacut. Novacut is an open-source video editor, but at least it's taking a slightly different approach than the other projects...