Originally Posted by pschirm
There is a reason bike manufacturers are using carbon for frames. In one of my materials classes (going to school to be a Mechanical Engineer) they showed us a piece of carbon that was 3 layers thick, 1" diameter around and 2" tall and they put it in a machine to test the compressive stress of it and it didn't crack until over 3 TONS of force were put on it. I know that the carbon being used for bikes isn't that extreme, but carbon is being used for a reason, it's strong and durable, much more than aluminum or steel. The weight of your bike hanging by the seat post is nothing to worry about. Like mentioned above, wrap it in something to keep it from getting scratched, but don't worry about anything breaking.
I'm assuming the orientation of the carbon tube was so the loading was axial? If the tube were placed on its side in such a test, I'm sure it wouldn't fair as well. CF is fairly isotropic, and while strong, it is not crush proof.
That being said, I think the majority of owners are a bit paranoid about how fragile their top tubes are. It isn't tin foil, fer cryin' out loud.