Anybody who chooses to compete for an Olympic medal assumes the risks associated with their decision.
Shit happens.
That being said, the hosts should be required to provide the highest possible standards and safety precautions and be held liable for negligence.
The design of the luge track in Vancouver was ridiculous.
People were worried that the track was very fast and dangerous.
So they have massive steel girders lining it after a wicked turn with basically no barrier?
http://www.youtube.com/watch?v=y_-6FqBB45w