I thought about getting some gloves with carbon fiber reinforcements when I was a biker, and didn't after someone mentioned how the carbon fiber shatters in an impact. I didn't want to worry about those tiny sharp pieces cutting my hands if I ever fell off my motorcycle, and still don't want to do that on my bicycle.
Well, I got them, and for one thing, it isn't carbon fiber but rather some sort of hard plastic. They seem to provide some level of protection for the knuckles ... I tried punching the wall a few times with them on and I barely felt a thing. So this will probably be good if I take a really nasty spill off a bike and my palm ends up facing the sky or something.
On the palm side everything is rather thin but I think it'll hold up for one spill off a bike.