[nullc]

While the factual you said we're true, they aren't anywhere near as useful as just linking to a calculator— http://people.xiph.org/~greg/attack_success.html

I don't agree with your conclusions though— at 40% a determined attacker reorgs 6 confirmations with a 50% success rate. Many users don't wait even six.

Consider, even with 20%— thats analogous to having five parties 'signing' blocks— a result which is less decentralized than a fair amount of traditional financial systems. (The comparison is better than it would be with other pools because ghash primarily physically controls their own infrastructure).

Even though this is all quite concerning, Bitcoin is very dynamic— the current state isn't something that will last, one way or another.