Sorry i should have said,
part of the nipple broke and fell into the hub, the bit of the nipple left in the rim was deformed and broken. the spoke also broke at the just where the threads enter the nipple. (maybe when the spoke broke the force also broke the nipple...)
The part of the nipple left in the rim protrouded into the hub thus damaging the brake shoe as i braked going down the hill, the loose part in the hub seemed to have jammed between the hub wall and the shoes.......thus jamming the wheel.
To be honest this happened a few months ago but this is what happened as i recall. I just wanted to see if anyone else had heard of, or had this happen to them,,,,,,
I can imagine brake internals jamming in the hub also......god those bloody drum brakes.....