Novacut is a work-in-progress HTML5-based collaborative editor that is currently fundraising on Kickstarter. It will run as a desktop application, but will also be made available in an online incarnation, and the entire project is open-source. It's different from established NLEs like Avid, Premiere Pro, and Final Cut Pro in that it's being designed from the ground up to allow editors to collaborate in real time over the internet. Here's Arin Crumley (Four Eyed Monsters) and Christie Strong on the NLE:

Video is no longer available: www.youtube.com/watch?v=CVrnKRQVsoE

The idea of collaborative online editing sounds very bandwidth-intensive, but the team seems to have it worked out in theory:

Novacut works with local files. Once your teammates have the needed media files locally, only changes in the metadata describing the edit must be synced between you, and this is tiny data, takes very little bandwidth. Getting the files in the first place can be bandwidth intensive, but there are options. First, Novacut can work with lower resolution proxy version of the videos, which are considerably smaller than HDSLR video strait from the camera. Second, sometimes shipping a hard drive to someone is the most practical, and dmedia has been designed with this use case in mind. And third, dmedia will soon be able to do a distributed upload (multiple people uploading files at same time) as a way to work around relatively slow upload speeds.

Here's their Kickstarter appeal.

There are some online demos but what I think would help tremendously would be to create a video demonstration of the editor in action -- it doesn't need to be a working demo, just something mocked up that will let potential users/donors know what to expect. Overall, it's going to be a very difficult undertaking, but a worthwhile one and I'm a backer. Check out the Kickstarter campaign here.