Will riding cobblestones and rough streets kill my cup and cone hubs? I live in pittsburgh, and we have some hills and streets which are belgian block, brick, poorly paved and pocked with potholes. It can be very jarring, but I still find myself flying down these streets running 700x28c tires at 100psi and I'm not a light guy at 200lbs.

Is this abuse going to damage my loose bearing cup/cone hubs?
Bearings and races are made of very hard steel. So long as they are properly maintained (lubricated and adjusted to the correct tightness; visit Free Ride in Pittsburgh for help lubing/adjusting your bike if it's feeling worn and you don't want to pay a shop to do it for you), they should hold up with no problem. 

More info:
http://en.wikipedia.org/wiki/Rolling_element_bearing