There were some carbon failures way back in the day that caused alot of attention. The truth is that currently, any reputable manufacturer that makes carbon components are totally safe. I'm sure that an aluminium frame would crack at a weld far before a new carbon component would. They are used in F1 as SAB said as well as the blades on blackhawk helicopters. Lamborghini, Pagani, Ferrari, and more use carbon chassis in their road cars. Now think about this, F1 cars generate about 5 g's under braking, lap after lap, day after day, with no damage to the chassis at all. Granted, it is more reinforced than a road bike but do you ever even approach .5 g? No.
Get carbon, any other material is far less optimum for road bikes (for racing anyways). If you brake it, you have FAR more to worry about than a mangled bike.