Lossless cutting (provided that your output codecs match your input codecs) is a feature of the "GStreamer Editing Services" library and thus will be part of the next release of Pitivi (barring unforeseen bugs of course - usual disclaimer applies: no guarantee, patches welcome for issues that may arise, etc.
Last time I tested (a year ago), this allowed rendering a project in 7 seconds instead of 5 minutes. Pretty cool if you don't need to apply any effects and just want to shuffle some cuts around quickly without losing quality.
Little known fact about Middle Earth: The Hobbits had a very sophisticated computer network! It was a Tolkien Ring...