Shimano Di2 Electronic Shifting
I saw this at Cycle yesterday on the Shimano stand, and had a go on the bike they had set up with it in a turbo trainer. The shifting is awesome, very fast and quiet - except for this electronic servo sound. The way the front mech trims itself as you go up and down the block at the back is also very nice.
I can't imagine wanting it on my bike though, there are lots of wires and batteries and control gubbins that just look way too ugly to hang off my Litespeed.
Also, Im not sure quite what they have solved with this, it weighs more, is more complex and prone to problems, and still just changes gear like the mechanical one did.