Tests have shown that latex tubes, like these Vittoria Latex Presta Tubes, can minimize rolling resistance by a few watts. Paltry effect you might say. But add in the weight savings of these 75 gram latex wondertubes, and you'll have a serious performance advantage -- lower rolling resistance and less mass on the outer diameter of the wheel -- meaning quicker accelerations and easier maintenance of speed. And when the difference between the top ten riders is a few percent and the difference between winning and losing is a few seconds or the length of a bike, you'll want all the advantage you can get.
An added benefit over standard butyl rubber tubes is a greater elasticity that enables them to be more puncture resistant. The only downside is that latex tubes are more porous than their black butyl counterparts. You'll need to air them up before every ride and if they sit a week or more, they'll appear totally flat.
The valve core is removable as well.
Note: For deep wheels, you can extend the valve with the Vittoria Valve Extention