This type of frame is getting to be more popular in the last couple of years. I make the frame out of a mix of Columbus tubes, mostly the Zona and Life series.
The hydraulic brake line goes inside the down tube so that it does not get in the way of the shifter cable routing. There's no cables at all on the tup tube of a frame like this so it has a clean look once it is fully built up.
This one will be paired with an Enve disc-road fork which I'll be ordering a couple of this morning.
The frame weighs 3 lb. 15 oz, only about 7 oz. more than the same frame in aluminum.