BitcoinTalk
Nenolod, the guy that wants to prove Bitcoin doesn't work.

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0.3.2 has some security safeguards to lock in the block chain up to this point and limit the damage a little if someone gets 50%.

But if someone has 50%+ of the CPU power and malicious intent, they can prove what it already says in the design document.
Typically, over 25,000 BTC.