Although I have Campagnolo, and there is limited ways of routing the cable/housing. I am curious as to what could be the shortest (and therefore lightest) way of routing the cabling on a Shimano system.

Here is how Zabel's bike has been done:

As you can see he has put the cabling back under the bar tape.

...that´s the Nokon cable set for Shimano! Anything special?

What I was asking was how the cable is routed, not what type of cable set it is.

Good Eye. I've never seen anyone route a cable like that. I would think such a sharp curve should be avoided, though. Got any close ups?

I have the cable routing on my Principia - check it out

Staggerlee

I've used a bike with cables routed like this. THey're a bit longer than the 'straight to the frame' route, and the gear change drags a bit, so it's slower to change because of the tight turn in the housing. It does work OK though (just not perfect).

I like having cables to hold onto in my road time trial position.

I'm more interested in the practicalities of shifting than reducing weight.

Cyclingnews did a report on his cabling.http://www.cyclingnews.com/road/2004/tour04/tech/?id=jul13-1

The problem with Nokon's is they sag when used with Shimano levers and look scruffy. They are concealed with ergo. I think that's why people have them concealed like in the picture shown. The main reason for using Nokon's is their lightness.
So, weenies are there other cables out there that are like normal one's but lighter. What about Jagwire and Gore et al. Would appreciate feedback.

Gore Ultralight, but not produced anymore

Does it affect the shifting at all?

The use of Nokon shifting cables under the wraps is an option. It takes a bit more of housing but it does not affect the shifing. Weight is no advantage with Nokon shifting cables, only brakes and routing under the wraps completely eliminates any advantage.

On my Nokons, I encased the segments in a very thin heatshrink tube which keeps them looking good and clean. It adds negligible weight and is clear, showing off the shiny bits well.