It's not opensource. "Lightworks isn't Open Source yet, so external programmers can't contribute to the core project right now, but I'm sure the Lightworks team appreciate their offers and enthusiasm. Keep watching RedShark for the latest on Lightworks."  

Taken from here: http://www.redsharknews.com/technology/item/512-lightworks-for-linux-first-ever-official-full-length-demo

I like the "yet" in there though.