I haven't read this entire thread yet, but is this true? The TX ID can be modified and re-broadcast to effectively double-spend? If this is the case, not only is MtGox justified in their issues, but they've also demonstrated to the entire world how stupid this community is to believe BTC is without flaw and can't be taken to $0 if the right individuals were to go through this protocol with a fine-toothed comb. What a terrible concept to implement. What is the purpose of a TX ID if not to identify a TX? What could possibly be achieved by allowing such an ID to be modified?