I'm interested to see if a flurry of crypto-currencies develops into a bubble with all the craziness that could mean. I'm not sure on the defenseability of BitCoin to filtering by ISPs as could perhaps be mandated by the government. If driven underground what would the reaction be?
My main thought is that it doesn't really matter if its filtered by ISPs, or if it's impossible to shut it down because they can't stop the hackers, man...
If the government of the US decides it's illegal and declares businesses and individuals accepting BTC to be trading illegally, then the value will undergo a significant collapse as it's now no longer the way of the future but just a secret internet thing (in the US). If a few other countries follow along then all dreams of BTC as the new global internet currency and transfer medium fail.
Bitcoin may not be the easiest thing to shut down due to its P2P nature, but that doesn't mean it can't be effectively destroyed by people in power.
